I read on the internet about Gliese 710, this is supposed to be a star on its way to our solar system, but how long will it take to get there? Was that 1.5 million years?
Answer
This star is now about 63 light-years from us, but it’s getting closer. We can deduce the latter from the doppler shift, which indicates the component of velocity towards us, and the so-called proper motion, the velocity in a direction perpendicular to our own. We can only know how close it comes to us if we could measure its motion with infinite accuracy, which is impossible. It is estimated that it will be at its closest approach in 1.4 million years, when it will be about 1.1 light-years from us.
1.1 light-years from us, which is four times closer than the star now closest to us, but still quite far. It still corresponds to about 70 thousand times the Earth-Sun distance. If we realize that the farthest planet is only about 30 times as far from the sun as we are, then that 1.1 light-years is still more than 1000 times further than the size of the planetary system. The solar system extends beyond Neptune, yet not 1000 times.
All those numbers are somewhat uncertain, because the measurements aren’t perfect. The answer to your question is quite robust: within 1.4 million years it will come closest to us. But whether she ‘reaches the solar system’ with that, I dare not say.
Answered by
Prof. dr. Christopher Waelkens
Astronomy
Old Market 13 3000 Leuven
https://www.kuleuven.be/
.