Apophis-is-back

Apophis, The Most Infamous Asteroid Around, Is Coming For a Visit.

Apophis is one of the most infamous asteroids in history, and now it seems to be back in the spotlight lately, as astronomers prepare to get the last good glimpse of the asteroid before the well-known 2029 “impact.” 

Relax, fellow readers of mine, this is not an apocalyptic article telling you to pack your stuff and move to Mars, although there are lots of them over the internet, and writing from Mars seems like one of the best ideas for me. But for now, let’s dive deeper and find out what’s the thing with this Apophis asteroid, what’s happening with that “good glimpse,” and what on Earth is the “impact” in 2029?

Apophis asteroid
Orbit of asteroid Apophis (pink) in contrast to the orbit of Earth (blue). The yellow dot represents the sun. Apophis takes 323.6 days to orbit the sun. Earth takes 365.3 days. Image via Phoenix7777/ Wikimedia Commons.

First things first, we are talking about asteroid 99942 Apophis, in its full name. 99942 because why not? (just kidding, I’ll explain in a moment), Apophis, because of its close approaches to Earth, made this asteroid appropriate for being an Egyptian “demon serpent who personified evil and chaos.” And then we wonder why this asteroid is considered so scary. Well, let me use the Apophis thing to get a little bit more into the general topic of asteroids (we are supposed to learn something from here, other than hiding in the basement, right?)

Let’s get a bit more into asteroids

I guess most of you know what an asteroid is: a big chunk of rock floating through the Solar System, basically. Giant asteroids can be called planetoids, meaning that their size can still be considerable. Regarding their size and potential for damage, there is no joke, as most of you are aware that life was seriously threatened a few (65 million) years ago when an asteroid made most forms of life go extinct (the Cretaceous-Paleogene event).

Asteroids are mainly composed of minerals and rocks. They can be classified by their composition in three categories: C-type (carbonaceous), S-type (silicaceous), and M-type (metallic). They are mainly remnants from the formation of planets in the Solar System, or rocks too small to become planets, or just pieces of rocks torn apart by massive planets’ high gravity. What is for sure is that the Solar System has many of them. There actually is an asteroid belt in the Solar System, located between Mars and Jupiter.

Apophis, The Most Infamous Asteroid Around, Is Coming For a Visit. 2

Of course, many asteroids are just floating around because of various reasons, mostly misunderstandings with other significant objects that threw them away, guess how, with the help of the holy force of the Universe, gravity. As intuitive as it is to think that gravity can only attract things, it is good to know that it can also throw away moving objects. Anyway, asteroids are moving things all the time and thus susceptible to orbit changes over time. 

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What’s in the name?

Regarding the discovery or recognition of an asteroid, what is at the basis is that it all starts after an asteroid is observed in two consecutive nights by an observer. The process until naming is long, but that is how it all begins. 

After it gets recognition as a possible asteroid, it gets a provisional name. Mostly, it makes sense because it has the year the discovery has been made and a designation representing the time of the year. Asteroids discovered in the first half of January are designated with AA, AB, AC, etc. For those in the second half of January, it would be BA, BB, BC, and so on. For example, an asteroid discovered when I’m writing (February 14) would be provisionally named 2021 C something. Pretend it’s the second discovery. It would be 2021 CB.

If you want the asteroid to get a permanent name, you need to prove that it has been observed more times, and preferably from more locations. If let’s say, 25000 asteroids are discovered in a year, about 10000 get permanent names. Depending on its popularity, it can get various names, and you can do that by proposing a name to the Small Bodies Committee of the International Astronomical Union. 

So how did Apophis get its 99942 number? What is for sure, it is a permanent number, but the exact meaning I cannot tell you. I leave this upon my reader’s intelligence to find its meaning. 

So what’s with all the fuss about Apophis?

Well, it is a rather unusual asteroid, as it was first spotted in 2004 (June 19, if you want to be precise), and at first, its name was 2004 MN. Actually, when in 2005 its discoverers got the chance to name it permanently, they chose the name Apophis, also because they were fans of an SF series, Stargate SG-1, in which Apophis is a villain threatening the existence of human civilization.

Apophis asteroid
Because of the distance, asteroid 99942 Apophis appears as a small dot in this telescope image. Image via University of Hawaii.

After the first calculation, it seemed to pose a 3% risk of colliding with Earth. That was the most considerable number we’ve had for this asteroid. 3%. Still, it posed a threat. It was expected in 2029. Further calculations showed that a minimal threat could be expected in 2036, and then the date moved to 2068. But the problem is, we can’t really predict events happening in such a long time. So the fuss is really for nothing. Well, not really. Let me explain.

On April 13, 2029, the asteroid will pass above Earth’s surface at a distance similar to that of geostationary satellites, though it won’t come closer than 31200 kilometers. Impacts in 2029 and 2036 have been ruled out, and for the 2968 approach, the odds are 1 in 150000. Well, I’ll be watching from my Mars hotel, anyway. 

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The fuss is that such an event is sporadic, being an approach that happens every 1000 years or so. It will be a huge opportunity for scientists to study the asteroid, and even more than just looking at it, they will look at the effects high gravity has upon the asteroid. It may even destroy it. So, astronomers will all be waving towards the asteroid in 2029 and with hundreds of instruments in their hands (not really, but let’s keep it like that for the sake of the image). 

What’s happening this year?

Apophis will come rather “close” this year too, and it will help astronomers look closely at the hunk of rock and predict its behavior even more. All telescopes (metaphorically speaking) will be headed towards Apophis in March 2021. The NASA NEOWISE Infrared Space Telescope will be used, and the Goldstone Observatory will also work on the observations. Hopefully, we’ll get everything we want to know until the subsequent close encounters. On March 5, 2021, it will pass within 16.8 million kilometers of the Earth.

Learn astrophysics at home

Did you always want to learn how the universe works? Read our 30-article Basics of Astrophysics series absolutely free of cost. From the popular topics such as stars, galaxies, and black holes to the detailed concepts of the subject like the concept of magnitude, the Hertzsprung Russell diagram, redshift, etc., there is something for everyone in this series. All the articles are given here. Happy reading!

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