The easiest way to study astronomy is simply to go outside at night and look up. There are tons of interesting things that we can see in the sky, like the movements of the planets, satellites orbiting overhead, stars in our own galaxy, and (if your skies are dark enough) even other galaxies. Of course, sometimes the sky surprises us with things we can’t easily identify. In that case, come ask us about it and we’ll take our best guess about what it was (it probably wasn’t aliens).

The next step to backyard astronomy is of course to use a telescope. Telescopes are complex optical instruments that take time and practice in order to learn how to use. If you are having issues with your telescope, we will do our best to help you out so you can find more cool stuff to look at.

Don’t see your question in the archives below?

Stargazing

Why do I keep seeing the same constellations over and over again? When can I see my favorite constellation? (Beginner)

The visibility of constellations does indeed change over the course of the year. As the Earth travels in its orbit around the Sun, the direction “nighttime” points is different, meaning different constellations appear to be overhead in different months. This is seen in the diagram below, where the “nighttime” direction opposite of the Sun points in the direction of Leo around March, for example.

This means that Leo will be roughly overhead at midnight in February/March, and it will be visible later in the night in the months before and earlier in the night in the months after.

Draco and other very northern constellations are kind of a special class of constellations because it is basically always visible no matter the time of year. Because it is so close to Polaris (the north star) which stays stationary in the night sky, Draco just makes a small circle in the northern sky over the course of the year, never dipping below the horizon at higher latitudes. This is probably why you’ve been seeing it so often!

Are all visible stars in our galaxy? (Beginner)

Yes, all of the stars that are easily visible in the night sky are within the Milky Way galaxy, and most of them are even within our immediate neighborhood of the galaxy. We can’t even really see stars that are on the other side of the Milky Way because there is too much gas and dust in the way blocking our view. However, it is possible to see the Andromeda galaxy with your naked eye if you go to a relatively dark place away from city lights. If you want to see it, I recommend looking at this article.

Why can't I see a constellation during the month of its zodiac sign? (Beginner)

The months of the zodiac are not determined by what constellations you can see at night, but rather by what constellation the Sun is currently in. The Sun moves across the sky over the course of the year, travelling through 13 constellations: the 12 constellations of the zodiac plus Ophiucus. Its path can be seen in the image below:

The way the zodiac is defined is problematic if you actually want to see a constellation during its month though. Because the Sun is in Pisces in March, that means that all of the light from the stars in Pisces is drowned out by the light from the Sun! The constellation is too close to the Sun to ever actually be seen at night, so ironically Pisces is the hardest constellation to see during its month. If you want to see Pisces better, you will have to wait about 6 months until the Sun is on the opposite side of the sky and Pisces is directly overhead at night.

How often does Jupiter go behind the Sun and how long does it take to come back out again? (Beginner)

The event you are referring to is called a Sun-Jupiter conjunction or a superior conjunction of Jupiter and it should occur about every 13 months. Jupiter takes about 11 years to go around the Sun, so in the time it takes the Earth to travel around the Sun once, Jupiter has moved through 1/11 of its orbit, meaning that the Earth must travel for about another month to make up for Jupiter’s travel. However, because all of the orbits of the planets are not perfectly aligned with each other, sometimes Jupiter passes above or below the Sun instead of directly behind it.

I tried for a bit to find a reputable list of when these would happen and the best I can come up with is this website where you can go year by year to see when the conjunctions happen for all planets, Jupiter included. As you can see there, the next conjunction is on December 27 2019. To see what this conjunction looks like, I recommend using the free astronomy program Stellarium, which lets you track the movements of planets and stars over time. Setting the time to December 27th and looking at where Jupiter is over the course of the day, we can see that it is behind the Sun for about 16 hours this year. If you are interested in other years, I recommend you investigate them for yourself. In 2018, for example Jupiter missed the Sun by about half a degree.

Does the full Moon reduce the visibility of deep sky objects when it is down or just when it is up? (Beginner)

The reduced visibility caused by the Moon is due to its light scattering off of the atmosphere that lies between you and whatever star or deep sky object you are looking at. If the Moon is below the horizon, it likely cannot shine light on the part of the atmosphere that is above you, so its light shouldn’t wash out your view. However, if it is close to moonrise/moonset and you are looking on the horizon, you might still see some effects (just like sunrise/sunset).

Can someone on the Earth have the Sun directly under them? (Beginner)

The short answer is yes. Here’s a longer explanation:

The Sun traces a perfect circle through the sky every day. Think of it like the equator on Earth: it’s a straight line that curves completely around the sphere that is the sky, travelling around once per day. Because its path is perfectly symmetrical, anywhere where the Sun can be exactly overhead, it can also be exactly underneath you.

So let’s imagine that you’re standing on the equator on Earth on the spring equinox. At noon, the Sun will be directly overhead, and over the next 12 hours, it traverses half of its circle and winds up on the opposite side of the Earth/sky from where it started, meaning it is directly below you. We can put this in more concrete terms if we think about the perspective of two people on the surface of the Earth. Say you are in Ecuador at noon while you’re talking to your friend in Indonesia, which is on the exact opposite side of the world where it is midnight. If the Sun is directly above you, then it is directly below them, and vice versa.

This can be true of anywhere where the Sun can be directly overhead, and since the Earth’s axis is tilted at 23.5 degrees, that means it can happen anywhere that is less than 23.5 degrees latitude away from the equator. So if you are in Hawaii on the day in mid May/mid July when the Sun is directly overhead (called Lahaina Noon), then your friend in Botswana exactly on the other side of the world has the Sun directly below them.

Why can I see a star during the day? (Beginner)

What you are likely seeing overhead is the planet Venus, which can get so bright that it is visible during the daytime if you look in the right place. You can confirm this by looking for Venus before sunrise (it is very bright in the East in early morning right now) and then following it over the course of the morning to see if you still see it when the Sun is up. Most of the time, people don’t notice it because it just gets lost in the blue sky, but once you notice it, it’s fun to look for!

Where are the stars that we see in constellations? Would constellations look the same to people in other solar systems? (Beginner)

The stars in our constellations, like most stars we see in the sky, are mostly just bright stars that are close to us within our own galaxy. There is nothing fundamentally different about them compared to any other star other than that they happen to be close to us so we see them as being brighter than others. The shapes of the constellations are also just a factor of our specific viewing angle, and the constellations change in shape drastically if you change your perspective. Here are animations of how Orion and the Big Dipper look in 3D from different angles. So if you were to travel between solar systems, then the constellations would likely look completely different. Another factor is that the Sun and all of the other stars are constantly moving, so over time, constellation will bend and deform, as shown below:

Why does the Big Dipper change position in the sky each season? (Beginner)

This is a kind of difficult concept that requires some 3D spatial reasoning to really wrap your head around, but I’ll do my best to explain it simply.

As you probably know, the Earth is orbiting the Sun. This means that the position the Sun is in relative to the Earth will change over the course of the year, so if a person could fly out into space and stay still, they would see the Earth move from the right side of the Sun to the left side of the Sun and back over the course of a year. We mostly don’t notice this because we just define our days as “one full rising and setting cycle of the Sun in the sky”. It doesn’t matter specifically where the Sun is, it will still go up and come down every 24 hours and we call the period it is up “day” and the period it is down “night”.

The problem starts to arise when you realize that during the direction we on the Earth are facing during the day changes over the course of the year. Going back to the person who is floating stationary in space, they would see that in one part of the year, people in daytime would be looking left, and in another part of the year, they would be looking right. The direction of “nighttime” also changes over the course of the year, which is actually easier to notice because of the stars. Stars are essentially an unchanging background in the Earth-Sun system, meaning that as the Earth moves around the stars over the course of the year, the stars remain in the exact same place. This means that if you’re looking right at night in one part of the year, you’ll see different stars than you will later in the year when you are looking left at night.

So that’s why we see different constellations in different seasons in most of the sky. However, not all constellations are like this. Up until now, we have just been talking about looking left and right in the sky, but you could also look up and down and see stars too. As the Earth moves around the Sun, you can see different stars to the right and the left, but the stars that are up never get blocked out by the sunlight and never move. This is why you can see the North Star (Polaris) all year: that special star is exactly straight up from the perspective of the person floating stationary in space and you can look up to see it no matter the time of year (as long as you’re in the Northern Hemisphere).

The Big Dipper is kind of special amongst constellations because it is close enough to the North Star that most people in the Northern Hemisphere can see it all year. However, we still have to remember that “nighttime” is looking in different directions over the course of the year, so in a part of the year where nighttime is facing left, the Big Dipper will look like the upside down version of when nighttime is facing right. Its position is actually slowly changing positions with all of the rest of the stars (from our perspective), but because it is up and not left or right, it never gets blocked out by the Sun and we can always see it at night.

Has light pollution in the Silicon Valley grown significantly worse in just the last year or two? (Intermediate)

This is a difficult question to answer directly since light pollution is kind of hard to quantify, but the answer is probably yes.

For a long time, Lick Observatory had an agreement with the city of San Jose to keep their old and comparatively inefficient sodium streetlamps instead of upgrading to newer, more efficient, and more inviting LED lamps because sodium lamps are significantly easier to remove from astronomical observations (this is explained in much more detail here). Also, because they are more efficient, LEDs produce more light pollution per dollar, so cities are probably brighter than they would have been without the upgrade. For these reasons, it was in Lick’s best interest to keep San Jose from upgrading.

However, it seems that that agreement is no longer in place, since San Jose is now rapidly replacing all of their old lamps, as is shown in this map. This has likely led to an increase in light pollution (although I don’t have data to back that up). This problem is probably also compounded by other nearby Bay Area cities doing the same upgrade, washing out the sky at an increasing clip over the past few years.

This seems like a sad consequence of the continuous march of modernity, but if you want to fight back, I recommend looking at the resources from the International Dark Sky Association here to educate yourself more. You may be able to make some progress in your neighborhood, and if you ally with a local astronomy club then maybe you can make some more progress. Good luck!

I just checked and the Sun isn't actually in the constellation the zodiac says it should be in. Why not? (Intermediate)

Most people looking into astrology don’t take the time to actually check the position of the Sun, so I applaud the investigation. You’ve stumbled upon a fact not often brought up in astrology circles: though the signs are supposed to be defined by which constellation the Sun is in at a given time, modern astrology definitions are extremely imprecise. It may seem suspicious that all of the signs are the exact same length given that constellations vary widely in size, and that’s because the astrological sign barriers were arbitrarily defined and don’t really reflect the modern boundaries of constellations. If you actually compare when the Sun enters and exits each constellation, you get the chart below:

As you can see, in the beginning of July, the signs have already progressed to Cancer, but the Sun is still in Gemini! In fact, the signs and the position of the Sun almost never actually line up, which happens for two reasons. The first reason is something I already mentioned, which is that the constellations are not standard sizes. For instance, Scorpio is a very narrow constellation, so the Sun spends only a few days inside it before moving onto the next one, whereas Virgo is a very wide constellation, so the Sun spends almost a month and a half going through it. The Sun also spends a few weeks traveling through Ophiuchus, but that constellation for some reason doesn’t get to be part of the zodiac. These differences in timing make the start and end dates of each constellation/sign inconsistent. I should note that modern astronomical definitions of constellation sizes are also arbitrary, but they are at least standardized and consistent.

The second reason is something a little more abstract. The Western astronomical signs were defined by Greeks more than 2000 years ago, and since then, the Earth’s skies have subtly changed. The direction of the Earth’s rotational axis wobbles slowly over time, spinning around like a top every 26,000 years. So since these signs were first defined, the Earth has completed about 1/12 of a full wobble, meaning that all of the signs have moved around 1/12 of the night sky. Since there are 12 signs in the zodiac, this leads to the signs being off by 1 almost all the time, as you can see in the chart above!

I was watching a star and it blinked out for a second! What happened? (Intermediate)

What you might have seen is something called a stellar occultation, which is when an asteroid or some other distant body goes directly in front of a star from your perspective, causing a brief but noticeable blip in the star’s light. These are difficult to predict because they depend not only on time but on your specific location on Earth (much like a normal solar eclipse), and I can’t easily confirm whether there was one when you were observing. However, if you feel like doing more research to see one of these again, I recommend looking at this website, which publishes a long list of occultation events (I don’t think yours is on there), or you can calculate your own using the software on this website.

Why is the magnitude system still used? Why is it so hard to find more precise/scientific measurements

Astronomy is a really old science and has a lot of terms and definitions that don’t really make sense anymore, but we keep using them because that’s the way things have always been done. However, I think the continued use of apparent/absolute magnitudes still has some relevance, and that’s mainly that it produces human-digestible numbers for human-observable things.

Sure, I could give a number for exactly how many W/m^2 a star delivered to my eyeball, but it would be a really small number and it would actually depend on a lot of different factors that people don’t consider. When astronomers are trying to give a precise number for the apparent brightness of an object, they usually use a unit called a Jansky (named after a famous early radio astronomer) that’s equal to 10^-26 W/m^w/Hz. You’ll notice that there’s an added dimension of frequency in this definition, and that’s because the quantity that matters more is the flux density, not the flux. The Jansky tells you how much energy you expect in a given frequency/wavelength bin in your instrument, which is useful if you’re only looking at certain colors of light or if you’re taking a spectrum of an object. If I know that the flux density of an object is .01 Jy and I’m looking a passband of 100 Hz then I can expect a total of 10^-26 W/m^2 in my telescope. The spectral data that I use has its fluxes given in units of ergs/s/cm^2/angstrom, which includes several nonstandard units but is common among visual astronomers.

The point of all of this is to try to accurately capture how much energy is being delivered at each wavelength, and the reason things are given in these terms is because it’s much harder to figure out how much energy an object is delivering across all wavelengths. If I wanted to calculate the total energy flux from a star (called the bolometric magnitude) I would need a radio telescope, a microwave telescope, a space-based infrared telescope (to get away from the effects of the atmosphere), a visual telescope, and separate space telescopes for UV, X rays, and gamma rays. Once I had measured the amount of energy coming off of the star across the full wavelength range of each of those different areas of the spectrum (this may require multiple different kinds of telescope per spectral range) then I could finally add up all of the flux density to get a total number for the full bolometric flux. Not necessarily easy (unless you’re just making a theoretical model of the object in which case you can do whatever you want), which is why we usually use flux density instead and why it’s hard to find flux numbers in W/m^2.

So why is apparent magnitude still useful? Because it’s defined in a useful and easy to understand way. The modern system (called AB magnitude) is still somewhat based on the idea that Vega should be magnitude 0, though nowadays it’s defined in terms of Janskies instead. This allows for astronomers to integrate over a given passband to express brightness over a wavelength range, and the logarithm out front makes everything come out in easily digestible numbers. This collapses the entire range of brightnesses down to basically -30 to +30 for the brightest and dimmest things, which is much less intimidating than always dealing with large negative exponents. They’re particularly for amateur astronomers (or high schoolers) who can live basically their whole lives between 0 and 10, and the passband used most often mostly lines up with the human visual range as well.

So while the logarithm and the extra steps are annoying to have to compute in high school astronomy class, the alternative of dealing with the nuances of actually precise flux density measurements is much worse. So even though it’s a fundamentally arbitrary system that we still use because the Greeks thought it was a good idea, it still actually makes some amount of sense for naked eye observing.

The Moon

If a Blue Moon refers to seeing two full moons in a single month and it's supposed to be rare, then why have I seen so many full moons recently? I witnessed at least 3 full moons this week alone! (Beginner)

You are right in noting the implications of the phrase, “once in a blue moon.” It means something happens only rarely. And, indeed, these events are quite rare – occurring only once every couple of years.

What you are seeing when you are seeing what looks like multiple full moons, is actually just the normal phases of the moon leading up to the one-day-long full moon. On the days surrounding the full moon – when the moon is 100% illuminated – the moon may appear fully illuminated, but it is, in fact, only 98% illuminated. That’s a minute difference and very hard to pick out with the naked eye, making it look like the full moon is lasting for three days.

Since a full moon only happens once per lunar cycle (which lasts 29.5 days), full moons only show up every 29.5 days. Since our months are 30-31 days long, if the day of the first full moon lines up with the first of the month, then the beginning of a second lunar cycle – a full moon – will fall in the same month.

Look out for the next month with a blue moon in August of 2023!

Is it possible to have multiple lunar eclipses in a row? I saw a red moon 3 times this week (Beginner)

Lunar eclipses can only happen when the Sun, Moon, and Earth are in a perfectly straight line like this:

This alignment only happens for an hour at most as the Moon moves around its orbit, and once that hour is up, the Sun, Moon, and Earth are out of alignment again, so another lunar eclipse can’t happen for at least another month. Because the alignment has to be perfect, lunar eclipses don’t happen every month, instead requiring exact alignment of the orbits to happen. However, when they do happen, it doesn’t matter where you are observing from: the Moon will appear to be in shadow to everyone who can see it.

If you saw the Moon looking red multiple nights in a row (and in phases that were not full) then the red color must have been caused by something else, probably smoke or pollution in the atmosphere. If you’re interested in seeing a lunar eclipse, the next one is in November, but it won’t be visible from Cyprus.

Is there such a thing as simultaneous sunset and moonrise? (Beginner)

If you observed the Sun setting at the same time as the Moon was rising, that would mean that the Sun and the Moon are in exactly opposite parts of the sky. This happens every month at the full moon, where we know that the Moon is opposite the Sun because its entire face is lit up from our perspective, so the full Moon rises right when the Sun is setting.

The Moon’s orbit varies slightly though, meaning that there may be a very small difference between rise/set times, but we know that they are exactly opposite during a total lunar eclipse because the Earth is perfectly between the Sun and the Moon. So if you observed the Moon rising during a total lunar eclipse, it would be at pretty much the exact time the Sun was setting.

If we can see the Moon during the day, does this mean that the other side of the world has no moon at night? Or is it possible to see the same Moon from the whole Earth? (Beginner)

First let’s consider the 3 celestial bodies that matter in this situation: the Earth (the big rotating thing you’re standing on), the Moon (the thing you’re looking at), and the Sun (the thing that decides whether it’s daytime or nighttime).

At any given moment, these 3 bodies are arranged in a specific orientation in space that only changes very slowly as the Moon goes around the Earth and the Earth goes around the Sun. This means that from the perspective of the Earth (and anyone standing on Earth), the Moon and the Sun will appear to be a certain distance away from each other. If the Moon and the Sun appear to be near to each other, then the Moon will mostly be up during the day, and if the Moon is on the opposite side of the sky from the Sun, then the Moon will mostly be up at night.

As the Earth spins around for a day, this arrangement of celestial bodies stays essentially the same, meaning that if you saw the Moon relatively close to the Sun during the day, then 12 hours later, someone on the other side of the world would be able to see the Moon relatively close to the Sun during the day as well. So we all see the same sky (this applies to stars and planets too) because it’s not the sky that is moving, it’s us spinning around in place as the Earth rotates. Here’s a fun website to play with this system and maybe help you get a better feel of it.

Why is a new moon different from a solar eclipse? (Beginner)

Both a solar eclipse and the new moon are caused by the Moon, Earth, and Sun falling in alignment. So, why doesn’t a solar eclipse happen every month?

The short answer is that the moon’s orbit around the Earth is tilted relative to the orbit of Earth around the Sun.

Let’s imagine there is a big flat sheet running through the Earth and the Sun. That sheet is called the “plane of the ecliptic” (named after the eclipse!). The Earth travels around the Sun along this plane, as do most of the other planets. The moon doesn’t. The moon’s orbit is tilted 5 degrees relative to the plane of the ecliptic. It is because of this tilt that the moon doesn’t perfectly align with and block the sun on every new moon.

The moon is still between the Sun and the Earth, but it only hits that sweet spot of intersecting with the plane of the ecliptic and with the line between the Earth and Sun once every 18 months. We don’t see a solar eclipse from our backyards every 18 months because the shadow of each one is only 165 miles wide and falls on different parts of the Earth, including the ocean, during each eclipse.

Amazingly, ancient cultures across the world were able to use early astronomy to predict exactly when and where the next eclipse will occur! Modern astronomers can do the same to tell us that the next solar eclipse in the US will be April 8th, 2024, and it will be visible from Texas.

There is a great video from the San Francisco Exploratorium that illustrates the role of tilted orbits in the solar eclipse: https://www.exploratorium.edu/eclipse/video/why-dont-we-have-an-eclipse-every-month.

How much does the Moon's position change when observed from different latitudes? (Intermediate)

This question has been around for thousands of years, and ancient astronomers used this technique to measure the distance to the moon for the first time. The basic setup of the system looks like this:

Looking at the moon from different angles means that it should shift with respect to the background stars (considered to be at infinite distance in this case), a concept called parallax. If there were two observers looking at the moon from the North Pole and South Pole simultaneously, they would perceive an angular difference of 2 theta = 2* arctan(earth radius / moon distance) = 1.88 degrees, so they would see the moon as being almost 2 degrees different in position. Since the diameter of the moon is only about half a degree, that means that the moon can move almost 4 times its size depending on where you are observing it from! The person on the North Pole could also see 1.88 degrees further north on the moon’s surface, which corrensponds to (1.88 deg) * (moon radius) = 57 km or 35 mi, so not that much, but certainly a bit.

I read that the moon formed because a huge asteroid or little planet hit Earth and a piece of Earth broke off and went into orbit and that piece is the Moon. If that is so, why is the Moon round? Where is the huge crater on Earth? (Intermediate)

I think all of your questions will be answered at the same time by watching the video of a simulation of the impact that formed the Moon on this website. I’ll break down the information contained in it to answer your specific questions though.

As you can see, the collision that formed the Moon didn’t break off a “chunk” of Earth and send it into orbit, it really just splattered lava in a giant collision. The Earth is not one solid spherical rock. Instead, it should be thought of as a thin shell of rock floating on thousands of miles of molten lava, and this was even more true 4.5 billion years ago when this collision happened. If anything large enough to break through the outer layer hit, it would spray out the lava in liquid form, not break off a big chunk. Once the lava is out in space, its own gravity will pull it into a sphere, just like water does in a raindrop or in space.
There isn’t a huge crater on Earth because this collision essentially destroyed and remade the entire planet. The planet’s shape was so disrupted that it essentially had to reform itself into a sphere again, smoothing out any irregularities that may have existed before. In addition, the massive amount of energy imparted on the planet by the impact would have liquified all the rock on the planet, allowing it to flow freely.

Unidentified Objects

What is the bright circle next to the Sun in this picture I took? (Beginner)

What you saw in the picture was probably not a planet. Phone cameras typically can’t see anything that your own eyes can’t see, so if you didn’t see something yourself, then it was probably lens flare, which is when sunlight bounces off the lenses in your camera and creates reflected images that only show up in pictures. These reflections are often present in pictures of the Sun, like this one I just took outside of my house:

The blue dot in the picture wasn’t actually visible to my eyes, and it moved around if I changed the angle of my camera, so I can be sure that it was just a reflection inside of my phone and not something real. Hopefully this answers your question.

I saw something bright in the sky and through binoculars it looked like it was a crescent even though it wasn’t the Moon. What was it? (Beginner)

There are two explanations I can come up with for what you saw. The first would be Venus, which experiences phases in the same way that the Moon does. We can frequently only see part of the lit up side of Venus since it is closer to the Sun than us, so it does not appear fully illuminated when viewed through binoculars and appears as a thin crescent right now. It was about 40 degrees from the Moon when you saw it a few days ago and it would have been just above the horizon after sunset. Mercury was also very nearby Venus at the time so it is possible you mixed up Venus with the dimmer and smaller Mercury and though that Venus was a larger object.

The other possible explanation would be Jupiter, which was about 20 degrees above the horizon after sunset and about 30 degrees from the Moon. It does not experience phases nearly as much as Venus or Mercury do since we are almost always looking at it from almost the same perspective as the Sun (so we only see the illuminated part), but it has four bright moons that appear in a line surrounding it. It’s possible that if your binoculars were not zoomed in enough, the line of moons could have given the appearance of a crescent or other oddly shaped object, but I personally think this is not as likely as the other explanation.

Hopefully this answers your questions. I recommend using a free planetarium program called Stellarium for identifying objects you see in the night sky since it allows you to set any time and place you want.

When I was looking through my telescope I saw a white dot about the same brightness as the stars zoom by. It didn’t have a comet tail & wasn’t fast enough to be an asteroid. I could even see it with the naked. What was it? (Beginner)

Comets and asteroids take weeks or months to travel through the sky and meteorites typically last less than a second, so what you saw was likely a satellite orbiting Earth. These pass across the sky continuously and the reflection of the Sun’s light off of them can frequently be seen with the naked eye if you are in dark enough skies and looking at the right time of day. These satellites are only visible overhead for a few minutes at a time, so if you were looking through a telescope, it would have passed through the small field of view very quickly.

If you want to see more satellites, I would recommend putting your location into this website and looking at its predictions for when you can see objects passing overhead. The International Space Station is of particular interest because it is very bright and easy to spot if you know when to look, but you should be able to see many other satellites over the course of a single night

I took a zoomed in picture of star and it looks all squiggly, and it looks different in every picture I take. What is going on with the star? (Beginner)

There are two explanations I can come up with for why the star is getting distorted in the way you are capturing. The first is that stars are naturally distorted by the atmosphere, constantly changing their shape to observers on the ground. Different temperatures and densities of air bend light differently, as you may have noticed on hot days where you can see “heat lines” radiating from a hot road that distort light passing through them. Similar things happen in the upper atmosphere, turning an incredibly small point of light into a spread out, moving blob as seen in this animation on the left. Astronomers have to use very complex optical systems called adaptive optics to correct for this distortion and make it look like the stationary point it actually is (shown on the right).

However, I think the more likely explanation for this is more mundane, and that is that your tripod is probably getting blown around by the wind. Most camera tripods are built to be portable and light rather than solid and sturdy, so even if you’re not touching it, it is still probably moving around slightly with the wind. Most of the time, photographers don’t notice this slight wobble because they are usually taking short exposures during the daytime, but when you are zoomed very far on a star and are taking a longer exposure than normal to capture its light, you can see the effects of the wobble much more strongly. Most DLSR astrophotographers buy much heavier tripods with sturdy gears for positioning (rather than screws and ball joints) so they can avoid wobbling.

If you want to take better pictures of individual stars like this, I would recommend going out on a calm night and setting your tripod down on a flat hard surface (or even some hard blocks of rubber if you have them) to try to isolate any vibrations. Try to leave your tripod alone for several seconds before starting the exposure to give it time to settle down (some of your pictures look like they weren’t settled down yet since they have a long tail in one direction that shows the camera moved a lot right when the exposure started before settling down into a messy but contained blob). Also try not to move while you are taking your shots because vibrations from you walking can travel through the ground and wobble the tripod. You should be able get much stabler shots if you try these things, although you’ll probably never get to a perfect point because of twinkling and the fact that stars are constantly moving as the sky rotates overhead.

I just saw a line of dots following each other through the sky in a straight line before disappearing. What was it? (Beginner)

What you saw was almost certainly a set of Starlink satellites passing overhead. Starlink is a new project by private space company SpaceX to supply high speed internet worldwide via satellites, and to accomplish this, they have been launching tons and tons of satellites into Earth orbit. When they are first launched, they are much brighter and closer together, making for a very striking display, but over time, they spread out and get dimmer to look more like what you described. They are visible in these long trains until they enter the shadow of the Earth, which is when the Sun stops shining on them so we can’t see them anymore. These passes are predictable and there are a number of websites you can visit to see when the satellites will next be visible (this one will automatically detect where you are and tell you upcoming passes). Most passes are much dimmer than what you are describing so you probably got lucky!

I will also note that these Starlink satellites pose somewhat of a threat to the astronomy community. When these satellites pass through the field of view of a telescope, they mess up the picture that was being taken (see the diagonal white lines in the picture below from the DECam instrument in Chile). SpaceX is trying to modify the satellites and orbits to make them less disruptive to astronomy, but because they want to launch thousands and thousands of these into the sky, astronomers are still concerned about them polluting the sky.

I just saw a bright dot moving slowly across the sky trailed by a large bright cloud of dust. What was it? (Beginner)

The object you saw was almost certainly a rocket launch. When rockets are launching into space, they expel large clouds of gas from their engines. Under normal circumstances, these clouds aren’t visible, but when the conditions are just right (when the ground that the rocket is above is dark but the rocket is high enough in the sky that it is still in the sunlight), the clouds of gas are lit up in such a way that they are visible to people on the ground. Here’s a very dramatic video from a few years ago showing the phenomenon.

Without knowing where and when you took them, it’s hard to say for sure which rocket launch it was, but assuming you’re in the southeastern US and you sent these pictures to me almost immediately after taking them, it was likely the SpaceX rocket launch of the GlobalStar communications satellite from Cape Canaveral at 12:27am EDT on June 19th. I believe the stars in the backgrounds of your pictures also confirm this. Here’s a video showing the launch moving across the sky looking very similar to what you were able to capture.

What was that flash I just saw in the sky? (Intermediate)

I will say from the start that I don’t have a super satisfying answer for you, but I’ll do my best to give you a few explanations for what this could have been, although it’s impossible to know for sure.

This likely wasn’t any astrophysical source (meaning anything to do with stars or other objects outside the solar system) since there aren’t any known processes that have that kind of visible brightness fluctuation in that short of a time. There are variable stars that change can brightness by up a few magnitudes over the course of several days and there are novas supernovas that undergo massive increases in brightness over the scale of a few months, but these wouldn’t look like a flash in the same way you saw.
There are other types of astrophysical sources that are currently poorly understood, like short gamma ray bursts and fast radio bursts, that can vary over those short of timescales, but those have never been detected with normal visible light. Since one of these would have to be very close to Earth in order for it to be seen by the naked eye, any effect would have undoubtedly been detected by other observations and would have been very big news in astronomy. I haven’t heard anything about this, so I don’t think this was one of those.
You are right that Iridium flares can cause large brightness spikes over the course of a few seconds as their reflectors catch the sun and shine it into your eye, but other satellites can do this as well. There are many satellites and debris orbiting the earth that are rotating in random and unpredictable ways. Sometimes these catch the sun momentarily and increase the brightness for a short time. The time you said you saw this lines up with the times we would expect to see satellites, and the light from satellites can also appear orange when it is about to enter the earth’s shadow and it is seeing the sun through the earth’s atmosphere (similar to a sunset). I personally have seen satellites that quickly increase their brightness and others that appear to be different colors.
Another more exotic explanation is the cosmic ray visual phenomenon, a visual effect commonly reported by astronauts. When high energy charged particles travel through a liquid (like the inside of an eye), they give off light due to a process called Cherenkov radiation. Astronauts see this radiation as short bright flashes coming from inside their eye every few minutes. In space, there are many more high energy charged particles because the earth’s atmosphere and magnetic field do a pretty good job of blocking them, so there aren’t nearly as many such particles on the earth’s surface, but there are some. It’s possible that some relativistic particle like a muon could have traveled through your eye and left a trail of light that you saw as a bright flash.
The least satisfying answer is that oftentimes the eye will just make up information. Human vision is pretty unreliable, and due to random chemical fluctuations in the eye, random neuron firing in the brain, or unsuccessful corrections of problems with human vision, we can sometimes notice mistakes in our perception. The most famous of these is the blind spot in the eye that can lead to things disappearing, but other things like seeing bright flashes can happen too. Most of the time, these things are not noticed because the things we are looking at are usually brighter and more varied, but if you look at something dark and uniform (like the night sky), irregularities in vision become more prominent.

Telescopes

I am a beginner looking for my first telescope. What should I buy? (Beginner)

Telescopes can be very complex and expensive, so for a beginner like yourself, it is probably best to start out small. People tend to buy telescopes, use them a bit, then never use them again, so the first place you should look are online markets for used goods like Craigslist or Facebook Marketplace or things like that. You should be able to find a relatively cheap telescope pretty quickly in the area around you. If I look around me, it’s mostly people selling old refractor telescopes for less than $100. These types of telescopes are good for seeing bright things like the Moon, planets, and bright star clusters, so they should be useful for starting out. I would also ask people you know if they have a telescope since a lot of people have old telescopes in a closet somewhere.

Once you figure out whether you really do enjoy using telescopes, you may want to look for more advanced telescopes. I would recommend an 8 inch cassegrain telescope with a computerized mount (like the Celestron 8se or the Meade LX200) as a good choice for getting into intermediate-level telescope use. These are obviously a giant increase in price, but they have some real advantages over cheaper telescopes. These will be a significant upgrade in light-gathering ability, meaning you should be able to see dimmer nebulas and galaxies if you have good skies. The computerized mounts will be able to find and track things automatically, which helps when looking for dim objects. Cassegrain telescopes get these benefits while still being small enough to be portable. If portability and ease of use are less important than cost, Dobsonian telescopes are a good middle ground. You can get a 6″ or 8″ Dobsonian telescope for around $500 that will have a similar light gathering ability to the same sized Cassegrain, but it will likely not have a computerized mount and it will be significantly longer, meaning it will be harder to transport.

Hopefully this information helps. You should always try to do your research before buying something telescope related because companies really like selling expensive (and overkill) optics to people that don’t know any better. Don’t be afraid to start small and work your way up over time.

My telescope is X big and can zoom in X far. How far can I see? (Beginner)

How “far” you can see with a given telescope is a difficult question to answer because it depends on a lot of things. Seeing “far” is much more dependent on the aperture of your telescope than anything else. Far away things tend to be dimmer (though not always), so the wider aperture you have, the more light your telescope can gather from a distant dim galaxy, allowing you to see things that are farther away. With a 60mm telescope, you should be able to see the center of the Andromeda galaxy, which is about 2.5 million light years away. You may also be able to see some other relatively bright galaxies, like M82, which is over 11 million light years away.

How far you can see is also affected by how bright your skies are. Other galaxies tend to be dim and diffuse in the sky, meaning that if your sky is very bright from city lights, their diffuse glow will be drowned out and they will be difficult or impossible to spot. I recommend taking your telescope as far away from bright city lights as possible if you want to see diffuse things like galaxies.

Finding these dim objects can also be difficult, and zooming in more actually tends to be counterproductive for locating things in the sky. The more you zoom in, the smaller field of view you have, so it will take longer to search for an object. If your telescope came with multiple eyepieces, I recommend using the most zoomed out one (the one with the longest focal length) when searching for objects.

Why do planets still look really small in my telescope? (Beginner)

Planets are comparatively hard things to look at with telescopes because, despite the fact that they’re the closest things to us in the night sky, they’re really really small. For instance, Mars is only about 0.3% the size of the full Moon in the night sky right now, and Uranus is only about 0.2%! In order to resolve things that are that small, you may need a larger telescope. When things get that small, the blurriness of the atmosphere starts to become a serious problem, smearing out any details on the surface and making planets look like featureless blobs (although Uranus is already a featureless blob). If you want better observing conditions, you can wait until the planets are closer to the Earth and appear larger (Mars was 3x its current size last November because we were closer to it in its orbit). In the meantime, I would suggest looking at some deep sky targets like star clusters or nebulas, because even though they are further away, they will still appear larger in your telescope.

How do space telescopes like JWST stay pointed in the same direction for long periods of time? (Beginner)

Keeping a telescope pointed at the same spot for long periods of time is not actually as difficult as you might think it would be. On Earth, observatories have to contend with the rotation of the planet, the atmosphere, and gravity when they are trying to stay pointed at the same thing, but in space, none of that stuff is a problem. JWST will stay exactly where it is pointed, just like a person on the space station can place a pen in mid air and have it stay exactly still. The observatory has gyroscopes and thrusters inside of it to control the movements of the telescope that will point it correctly, and once it is there, it doesn’t matter if it’s orbiting the Earth or the Sun or whatever because there’s no external forces applying a rotation to it. The observatory can’t stay pointing in the same direction forever though because it has to always have its sunshield blocking the sunlight from hitting the mirror, so it does have to change where it’s pointed over the course of its orbit. For the closest objects that don’t stay completely still, like the other planets in the Solar System, the gyroscopes in the telescope have to make it rotate at exactly the correct speed to track the tiny movements through the sky that the planets make, but that isn’t too much harder than just staying still.

Everything looks blurry through my telescope. Is something wrong? (Intermediate)

I have a pretty good amount of experience with small telescopes, and without knowing for sure what you’re looking at or your view looks like, I can say that blurriness is normal. People often expect to see views like this in their telescopes, but in reality they get this or this (on a good night). The main problem here is the atmosphere. No matter how big a telescope you have, if it’s on the ground, it’s going to have to look through the atmosphere to see things in the sky, and the atmosphere tends to distort light and make things look blurry.

Large observatories have ways to correct for this, and other telescopes are launched into space specifically to combat this (the first picture up there was from the Hubble Space Telescope, which produces most of the cool astronomy pictures you see). The only thing you can really do though is pick a time and place with good observing conditions for the object you are looking at. If you look at an individual bright star, you will see its light fluctuate as it twinkles. This twinkling is the same atmospheric distortion that makes things blurry, so if you go out on a night where you have noticed the twinkling is less than normal, your view should be less blurry overall. Another thing to take into consideration is that things that are lower in the sky are blurrier too because their light has to travel through more atmosphere to get to you, so try to observe things when they are high in the sky.

With regards to the telescope itself, there are a few ways you can test your telescope to see whether there are problems with it. The easiest way to do this is to look at a somewhat nearby object like a the top of a tall tree in the daytime. You should be able to focus the telescope well on it and see lots of detail, but if it never comes into focus, that might be a problem (make sure the thing you’re looking at is far enough away though because telescopes have a minimum focusing distance). Another thing to try is to look at a bright star and defocus the telescope slightly. You should see a donut of light with the black hole in the center (this is the projection of the secondary mirror at the front of the telescope). If the star instead looks like the image on the right in this picture, then your telescope might be out of collimation, which can lead to blurrier images. There are probably instructions on how to fix this in the instruction manual for your telescope, but this is a difficult and finnicky process so I wouldn’t recommend trying it yourself unless it looks like it’s really uncollimated.

I would also recommend taking off the barlow because in general, things look better if you zoom out because zooming in on blurriness doesn’t help anything. It is also easier to look at things like nebulas or star clusters than it is to look at planets because they are not as small on the sky (even though planets are the closest things to us, they are really small in the sky).

How do I polar align my equatorial telescope? (Intermediate)

The process for setting up an equatorial mount isn’t necessarily easy. Here’s an article with pictures that describes how to set it up (and I’m sure you can find other sources by googling around), but here are the rough steps assuming you already have everything assembled correctly:

Use the declination adjustment (the topmost knob on your telescope) to point the telescope so that it’s as far up as it can go. It should read 90 degrees on the little silver wheel (as long as the wheel is correctly aligned, which I think it should be).
Take the telescope out and point it roughly in the direction of Polaris (the north star). Polaris is pretty easy to find (here’s a picture showing how)
Use a bubble level (or an app on your phone) to adjust the legs on your telescope until the bottom is as close to level as you can make it. This is much easier if you start on level ground. Make sure it stays level throughout the whole process.
Get the telescope exactly aligned with Polaris by using the bottommost knob on your telescope to adjust the telescope vertically and picking up and rotating the telescope to adjust it horizontally. This is a finicky process that can take a long time, especially if you’re not on level ground and have to keep releveling your tripod. Use your finder scope to point your telescope in basically the right direction first and only switch to the main scope once you’re well aligned in the finder scope.
Once Polaris is centered in your scope, tighten the bottommost knob to make sure it doesn’t move and don’t touch your tripod anymore. The angle that this joint makes with the ground should be equal to your latitude if everything went correctly.
Now your telescope should be aligned and you can use the actual controls again! If you point it at a star, the star should move out of the field of view within a couple of minutes, but you should only have to move your telescope’s hour angle (middle knob) in order to find it again.

If you go through with this whole complex process, the good news is that you don’t have to do it all again. You shouldn’t have to touch your bottommost joint again unless you change latitudes, so all you’ll have to do is point the telescope at 90 degrees declination and then rotate the tripod until you are pointing at Polaris again.

Why do pictures of stars through telescopes always have spikes? (Intermediate)

if we had an optically perfect telescope, then a star would appear as just a small disk. However, no telescope is perfect, and the optical imperfections are what ends up creating the spiky shapes you see. The scientific name for these features is diffraction spikes. I recommend reading through that whole Wikipedia article if you want a detailed description, but the basic concept is that whenever light hits a sharp boundary, it spreads out along that boundary, a process called diffraction. So because the secondary mirror of JWST (and most other telescopes) is held up by supports, the light spreads out along those supports and makes those lines that you see in pictures. In addition, the primary mirror of the telescope is made up of a bunch of smaller hexagonal mirrors, and the light hits the edges between each of those mirrors and spreads out along those directions as well. The different components of the final shape for JWST is shown in this excellent diagram:

So while the stars themselves aren’t “star-shaped”, the way that telescopes are constructed makes them look that way in pictures. Astronomers must have a full and detailed understanding of how a telescope spreads a point-like source of light (called a “point-spread function”) because if we can build an accurate model of it, then we can undo that spread computationally and figure out what the object we’re looking at actually looks like.

Can I attach some mirrors to a spare satellite dish to make a giant telescope? (Intermediate)

Amateur telescope making is a small but dedicated community of people who really know a lot about optics and the sky. Unfortunately, I don’t think you’ll have much luck making a serviceable telescope by gluing smaller mirrors to a dish. Though segmented mirrors are used in large observatories, they are incredibly complex systems that require a massive amount of engineering and precision to yield usable results. For instance, the Keck telescopes in Hawaii (the first large segmented telescopes) have motors able to make nanometer-scale adjustments to the positions of the mirrors, and the shapes of the individual mirror segments are extremely precise so that they focus correctly. You can also read about the alignment of the JWST segmented mirror here, which was a very complex and precise process.

So you won’t be able to use it for an optical telescope, but you may be able to use it to make a radio telescope if you want! The alignment required for those are much less precise, and the satellite dish should already have everything you need to make it happen. You can probably find some guides online to get everything you would need. And if you like DIY projects for optical telescopes, I can also recommend this guide for how to grind your own telescope mirrors so you don’t have to pay for your own (although I’ll warn you: it’s a lot of work and incredibly precise!)

JWST can see a tiny sliver of the Universe in great detail, while SDSS saw large portions of the sky in pretty good detail. Which is better? (Intermediate)

Often, when astronomers are talking about a new observatory or project, they will use exciting words to describe how their accomplishments, and which terms are used are often dictated by what the astronomer is trying to convince the public of. For instance, in the JWST image you’re referring to, the person who wrote that sentence was likely trying to emphasize that even that “tiny sliver” of the night sky contains innumerable galaxies, and JWST is able to see deeper into that tiny sliver than anything ever before to find distant galaxies. Every tiny sliver should contain similar wonders to this one (although they chose a cluster with strong gravitational lensing for a reason), so the goal of that sentence is to make you anticipate the discoveries to come. This is the same thing the Hubble Space Telescope was built to do, which is why you are probably hearing lots of comparisons between JWST and Hubble.

In contrast, SDSS was built to image large parts of the sky at a time, not just one part, which is why it was billed as taking a “detailed image of the universe”. It was revolutionary at the time since no telescope survey had come even close to producing the volume and quantity of data that it produced (data that I still use in my research today!), but each individual image was nowhere near as good as the images coming out of JWST. SDSS probably would have only been able to see the stars and the brightest few galaxies in the JWST image. However, its wide-field spectroscopic and imaging capabilities let it find the hundreds of thousands of quasars you mentioned, something JWST was never designed for. More modern surveys like DES, DESI, and the upcoming Rubin Observatory/LSST are following in the footsteps of SDSS in producing wide-field images and spectra of the Universe.

So really, JWST and SDSS are trying to do different things, but both of them are trying to sell themselves to the public and make their science goals sound cool. JWST is never going to take wide field images of the sky because it wasn’t built to do so, and SDSS could have never produced, so every team has to figure out how to make their telescope and its data sound cool to people like you.