## Fireballs From Space – A Journey Through Asteroids

(Last Updated On: September 2, 2019)

#### Journey Towards Asteroid

In the 18th century, 2 brilliant brains from Germany, Johann Titius, and Johann Bode formulated a law now known as ‘Titius-Bode law’ which gives the distance or position of celestial objects from the sun in ‘astronomical units’. The astronomical unit is the measure of long-distance for which the distance between sun and earth is considered as 1 A.U. which is 149.6 million km. The law gives us the nearly exact distances from the sun in astronomical units.

This law is formulated in 2 ways –

d = (x + 4)/10. or d = (2n * 3 + 4)/10.

Here d is the distance in a.u. x is the no. which gets double of its previous value every time starting from 0, 3, 6, 12…. If you consider 2nd formula n is the no. of celestial object or planet in order. The values obtained from the above formulae the values are nearly accurate up to Neptune.

Planets        Calculated distance (In A.U.)    Actual distance (In A.U.)

Mercury         0.4                                                           0.39

Venus             0.7                                                            0.72

Earth              1.0                                                            1.0

Mars              1.6                                                             1.52

Ceres             2.8                                                             2.77

Jupiter           5.2                                                             5.2

Saturn           10.0                                                           9.54

Uranus          19.6                                                           19.2

Neptune        38.8                                                          30.06

Planets found at a nearly exact distance except one at 2.8 a.u. distance. There wasn’t any planet in between Mars and Jupiter. Here investigation for the lost planet was started while there some scientists found an asteroid at 2.77 a.u. distance. Later scientists went on a spree of finding very small-sized, no. of asteroids at the same distance as there was this belt. And now we call it ‘Asteroid Belt’.

#### Then why there isn’t a planet?

There are some theories behind the presence of asteroid belt instead of a planet.

1. At first, scientists thought that it was the remaining part of our solar system when it was forming.

2. Some astronomers said that it was going to form but its gravity was too weak that it can’t bind together and shattered and started revolving around the sun.

3. Well, the reason which is popular and mostly accepted by everyone, why there isn’t a planet is Jupiter’s humongous gravity. Due to the gravity of Jupiter, the planet couldn’t form.

4. There is another theory that it was struck by another celestial object while formation.

The asteroids are very interesting celestial objects. Ceres is the largest of them having a diameter of about 1000 km. Asteroids are from 1000 km to even in some centimeters in diameter. They are very strange. They do not have a proper shape and size. They are very small in size and they are made from regular metals hence their mass is very less hence their gravity or gravitational field is very weak. Asteroids also rotate around themselves like other planets. If you land on an asteroid and you try to move the whole asteroid then it can move due to your move and you can be thrown out in any direction. So, if you think of landing on them, be careful.

#### Missions and researches on Asteroid

In 1991, Galileo satellite sent for Jupiter took the first picture of an asteroid named Gaspra. Then it took pictures of Ida from close angles. Then in 1996 a satellite is launched named ‘Near-Earth Asteroid Rendezvous’ (Near) later renamed as Shoemaker in the honor of scientist Shoemaker, which visited ‘Mathilde’ asteroid and took observations of it. Then it visited ‘Eros’ which is shaped just like a boat. Then there is ‘Castalia’ which came very close to the earth, it was a distance of 11 times the distance of earth and moon. Then there is an asteroid named ‘Vesta’, which has a diameter of 525 km. There is an amazing thing in asteroids they also have moons. Yes ‘Ida and Dactyl’ is one of them. Ida is big asteroid and Dactyl is its moon which rotates around Ida and very small in size.

These asteroids do not only rotate the sun by remaining in the asteroid belt, but there are some stranded asteroids which reach Earth’s or Jupiter’s path of rotation and they are called as ‘Trojan Asteroids’. These asteroids are one of the spectacular things in our ‘Cosmos’.

#### Difference between asteroids, meteors, meteorites

Asteroids are small celestial bodies, which move around the sun just like planets. Thus, they are also called planetoids. Meteors are the small chunks or any other celestial body or an asteroid, which burns while entering into the atmosphere, they are what we see and call as shooting stars. Not every meteor reaches the surface or land most of them burn in the sky itself, but there are few which strikes the land and the remaining part of that asteroid or that body is called as ‘meteorite’.

#### Why they are so important?

Around 65 million years ago a big asteroid struck to earth and that changed the face and fate of the world. In Chicxulub, Mexico scientists found a large crater and it was caused by striking of a large asteroid and when the dating is done it found to be around 65 million years ago at the same time when all dinosaurs became extinct. It is said that collision could be so terrible that dinosaurs and other animals and plants at the same place vanished in a blink of an eye. Then the parts of it, broken by collision, hit as fire mountains. Due to the collision, a tremendous amount of dust and soil would have spread on the air and covered the sky.

The collision could have caused earthquakes and volcanic eruptions in all other parts of the world. There would have been a long chain of earthquakes and volcanos over a long period (scientists think maybe for 3 years), because of which the dust and soil constantly covered sky (for 3 years). The gases from volcanic eruptions would have caused acid rain. Hence a small ice age would have appeared as sun rays not reached for years. And due to that a whole species which once ruled the planet earth disappeared from the face of the earth with some of the other species from animal and plant kingdom.

On these deadly asteroids, the world’s best astrophysicist Neil deGrasse Tyson said:

Asteroids have us in our sight. The dinosaurs didn’t have the space program, so they are not here to talk about this program. We are, and we have the power to do something about it. I don’t want to be the embarrassment of the galaxy, to have had the power to deflect an asteroid, and then not, and end up going extinct.

#### Bhalchandra Ravindra Yalamali

He is an astrophysics lover. He loves to explore the field of astrophysics.