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?
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.
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!
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.
- 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.
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.
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 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.
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.