What does it mean if a star is 100 light years away?

Information about the universe comes to us almost exclusively through various forms of light, and all such light travels at the speed of light—that is, 1 light-year every year. If a star is 100 light-years away, the light we see from it tonight left that star 100 years ago and is just now arriving in our neighborhood.

How many planets are in 100 light years?

All the 24 exoplanets are located over 100 light-years away. However, Schulze-Makuch said this study will help future telescopes set targets easily. “We have to focus on certain planets that have the most promising conditions for complex life.

How many light years away are stars?

The closest star, Proxima Centauri, is 4.24 light-years away. A light-year is 9.44 trillion km, or 5.88 trillion miles. That is an incredibly large distance.

How far away is 100 million light years away?

100 million light years is very far away. The only stars we can see that are that far away are stars that are in the throws of a violent supernova. Such stars will generally become a black-hole (and cease being an ordinary star) within days, let alone millions of years.

How old are stars in light years away?

A single star at a 100 million light years away that we observe today (photons of it reaching us now) can now be a 100 million to perhaps trillions of years old, but only if it is still alive now.

What is the lifetime of a star?

A 30 sun mass star has a predicted lifetime of about 11 million years and a 60 sun mass star has a predicted lifetime of only 3 million years! Stars even bigger than that can die within perhaps a million years.

Is it true that the light we see comes from old stars?

No, it means that the light we’re seeing is that old, since it took 100 million years to reach us. The star might be billions of years old, and could even have since died. Light years are a measurement of distance, not time.