Is the cost of space exploration justified?

One of the brightest comets of the 20th century was comet hyakutake, which passed close to the sun in early 1996. the orbital period of this comet is estimated to be about 30,000 years. find the semi-major axis of this comet’s orbit. compare it to the average sun-pluto distance and to the distance to alpha centauri, the nearest star to the sun, which is 4.3 light-years distant.

Can someone me? i need to have this done as soon as possible! i'm putting 20 points on this!

At which boundary does subduction stop occurring, resulting in a mountain range?