A Guide to Satellite Flares

update: Unfortunately, the last of this generation of Iridium satellites have reentered and so no more Iridium flares. In the meantime you can check out the ISS and other bright satellites.

So you have seen the International Space Station (ISS) and you are all amped up about seeing more man made objects in space. Oh you haven’t seen the ISS? WHAT ARE YOU DOING WITH YOUR LIFE?!?!? Just kidding. But if you haven’t seen the ISS, I highly recommend you check out this article first.

Now that we are all on board for having seen or planning to see the ISS, lets move on to how to see other satellites. Although satellites don’t have an entire football field of solar panels to reflect sunlight onto the Earth, like the ISS, satellites can at a certain angle reflect sunlight onto the Earth making them appear very bright (brighter than most starts). This phenomenon is called a Satellite Flare.

The most common satellite flare comes from the Iridium satellite constellation (satellite constellation is just a fancy name for a group of satellites that work together). Thus you might see the term Iridium flare more often than satellite flare.

How do you see it?!? A couple things to note before you go hunting for flares. They are unlike the ISS in that you won’t see them making a pass over your whole horizon. They typically will be in one location of the sky and appear as nothing, then become a dim star, and then turn to become more brilliant than the stars around. They can get even get brighter than the planet Venus! But it is important to note that they will not be moving; rather they will be around the same location the entire time you’re observing them. Now, there are many services that will help you spot a flare based on your location but I have my favorites (that are all free).
If you have an android, you are in luck because the app I recommended for the ISS also has a feature to notify you of satellite flares. It grades the flares and gives you directions on where to look just as it does for the ISS so it is very easy and familiar to use.
If you have an iPhone, you will need to download the Sputnik! App. Although it isn’t my favorite for the ISS because it doesn’t do a good job of showing where in the sky the ISS will be for the entire pass, it is perfect for satellite flares because satellite flares don’t move much in the sky. This app tells you how bright a flare will get based on its apparent magnitude (a unit astronomers use). If you aren’t familiar with apparent magnitudes, DON’T SWEAT!! Here are some examples to give you an idea of exactly how bright the number you are looking at is. The brightest stars range from 1 to -1.5. Venus ranges from -3.8 to -4.9. The key to apparent magnitudes is that the smaller the number the brighter it will be. Now as for where to look, when you click on a sighting it says “show device orientation” at the bottom. When you click this, some numbers will come up with arrows on where to redirect your phone to get the elevation and compass direction you are searching. These instructions are different than how most skymap apps work. Instead of pointing the camera towards the area of the sky you are looking, you are pointing the top of your phone to that area. It is as if you had a laser shooting out the top of your phone,and it would point at where you need to look in the sky. So if it tells you to hold your phone vertical (90 degrees) you should be looking straight up. This can take some getting used to for the elevation, but luckily the flares are so bright they are hard to miss if you are looking in the general direction.
If you hate phones or phone apps, check out this website. Scroll down until you see a line of blue buttons. You must manually set your location by hitting “set location” and entering your latitude, longitude, and elevation (google your city or use the compass app on your phone to find this). After you set your location, click “predict flares” and voila it will give you some sightings. This uses apparent magnitudes also but it gives you a rating along with it! This is a little more complicated in finding where to look so feel free to ask me any questions. Such a hard life without smartphones….

I really hope I didn’t bog you down with too many instructions. Feel free to come back to this page when you are actually observing the flare. Flares are so bright you really don’t need to stay away from bright lights like your phone as if you were watching for meteors.

Now for the details on what you are actually looking at! The Iridium satellites were put into orbit by Iridium Satellite LLC (now Iridium Communications) as a global phone that would use satellites for communication. There about 95 of these satellites in orbit making your chances of spotting one fairly decent. The reason these are so reflective is due to those three solar panels you see in the picture. At the right angle they concentrate all the sun’s rays onto you! Oh and cellular signal…. The company started in 1997 but after people were unwilling to buy these pricey phones, they went bankrupt in 1999. This 5 billion dollar company was sold for a mere 25 million dollars. The company since has rebranded and its main customer is the US Department of Defense. You can get your own Iridium phone for about 50 dollars a month.

Iridium in recent years has been known for one of its satellites, Iridium 33, colliding with a retired Russian satellite, Kosmos 2251. This collision is especially important as Iridium 33 was a functioning satellite and it greatly increased the number of debris in low earth orbit. NASA also had trouble predicting how the satellite would break up because it is made of newer materials than its archives tests accounted for. This collision is often at the forefront of discussion about space junk and space situational awareness.

Happy Observing!