how do scientist detect incoming asteroids that is so far and would hit earth in years like 2035?

Answer 1

They detect asteroids by taking many, many pictures of the sky and subtracting the pictures. Stuff that stays stationary, like stars (at least relative to each other on short times scales) subtract out, and all you have left are moving objects - like asteroids.

If you watch how it moves over several nights, you can figure out how it is moving relative to the Earth, and from there figure where where it is and where it will go.

Answer 2

"Incoming" is totally the wrong word.

The asteroids that are likely to close approach Earth are all in what are called Earth-crossing orbits. The 2035 close approach is not approaching for all that time – it is in an orbit that is predictable, and which they have shown will cross or come near earth’s orbit at that time.

The ability to work out the orbits of asteroids, comets etc has been known since the days of Halley (that is why the comet was named after him, because he worked out its orbit and was first to predict its return).

Answer 3

By plotting the orbit of an asteroid vary carefully they can easily calculate where it will be in 10, 50 or even 100 years. In isn't any harder than predicting where Mars will be in the future or when an eclipse will occur.

Answer 4

By looking for them through telescopes, but they miss seeing an awful lot of them. For example, in 1994 an asteroid (1194XL1) approached to within 65,000 miles of Earth and wasn't seen until AFTER it had passed by.

Answer 5

These asteroids have orbits that can be predicted. Once we figure out the exact orbit we can plot it ahead into the future and see if it crosses our orbit.

Answer 6

It is very difficult to predict where something will be that far ahead. All they can say is that its on an orbit that needs to be watched because it could come near.

Answer 7

One word: telescopes.