Asteroid Day — everything you need to know about the rocks in our solar system that could one day hit Earth

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  • The sixth annual Asteroid Day will kick off tomorrow, June 30.
  • Some of the most frequently asked questions (FAQs) about asteroids include — what is an asteroid, which asteroid is the biggest and if they really do pose a threat of hitting Earth.
  • Here are the answers to the 10 most common FAQs about asteroids.
Asteroid Day is just around the corner and there are many questions that people have about asteroids. From what exactly is an asteroid to if any of them really do pose a serious threat of hitting Earth one day.

Asteroid Day is celebrated on June 30 to mark the anniversary of the Tunguska event in 1908 which flattened 2,000 square kilometres of forest. This year, due to the coronavirus pandemic, Asteroid Day will be celebrated digitally with the events and panel live broadcast on the official site from Luxembourg.


Here are some of the most frequently asked questions (FAQs) about asteroids to get you ready for Asteroid Day on June 30.
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  1. What is an asteroid?
    Asteroids are small rocky objects that orbit the sun. They are the remnants from the beginning of the universe that never got a chance to turn into a planet — but scientists believe they hold the secrets to how our solar system was formed. Most of them live in the asteroid belt but can also be found in orbits around planets.
  2. What is the asteroid belt?
    The asteroid belt is the region between Mars and Jupiter where most of the asteroids in our solar system are known to orbit the Sun. The asteroid belt contains millions of asteroids. All asteroids come in different shapes and sizes. While some are less than a kilometre, others can be as big as Mount Everest.
  3. When was the first asteroid discovered?
    The first asteroid to be discovered was 1 Ceres in 1801 by astronomer Guiseppe Piazzi.
  4. What is the largest asteroid in the solar system?
    The largest and biggest asteroid in the solar system, by far, is 1 Ceres with a massive diameter of 974 kilometres. In fact, it’s so big that scientists have labelled it a dwarf planet in 2006. It’s the only object in the asteroid belt that has been rounded by its own gravity. It’s curst is 60% rock and the rest is ice. It takes 1 Ceres 4.6 Earth years to complete one orbit around the Sun.
  5. What are the other biggest asteroids in the solar system?
    The next largest asteroids in the solar system are 2 Pallas, 4 Vesta and 10 Hygiea which are between 400 and 525 km in diameter. All three also lie within the asteroid belt. Every other asteroid discovered so far is less than 340 km across. Making 2 Pallas, 4 Vesta and 10 Hygiea the biggest ones by far — second only to 1 Ceres.
  6. Can an asteroid hit Earth?
    The chances of an asteroid hitting Earth are slim — but it’s not impossible. That is why space agencies like the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are on a constant lookout for close-approaches. Once they spot an asteroid, it’s put on a watch list and the chance of impact is calculated to ensure that no asteroid slips between the cracks. However, spotting asteroids can be a challenge due to blind spots created by the Sun.
  7. What asteroid is most likely to hit Earth??
    The asteroid that has the highest likelihood of hitting Earth according to the ESA is 2010RF12. There’s a one in fourteen chance that it could crash into the planet when it makes its close approach on 5 September 2095. The asteroid is only 9 metres in diameter, so it probably won’t wipe out the planet, but the ensuing impact could still be devastating depending on where it lands or explodes.
  8. What asteroid is most likely to hit Earth in 2020??
    The top 10 asteroids that hold the highest risk of hitting Earth also includes an asteroid that set to make its close approach on 2 November 2020. There’s only one in 193 chance that will actually crash into the planet and it’s also considerably smaller measuring only 2.4 metres in diameter. So, Asteroid 2018VP1 is on the risk list — it is not on ESA’s priority list.
  9. Why is it important to study asteroids?
    Scientists believe that asteroids are leftover from what should have been planets when the solar system was born and could hold secrets to the early universe. In addition to the academic insight they could provide, asteroids contain resources.
  10. What kind of resources do asteroids have?
    NASA’s studies have determined that there are two types of asteroids that could be of interest to the mining community — achondrites and chondrites. The first group of asteroids are rich in platinum group metals like ruthenium, rhodium, palladium, osmium, iridium and platinum. The second group of asteroids are rich in water — a resource running out on Earth and is even more rare to find in outer space.
SEE ALSO:
Asteroid Day is next week — top five things you need to know

Asteroid Day is on June 30 — and it’s the one day no asteroid will be making its close approach

The 10 biggest asteroids that pose a threat to Earth in 2020