What is the oldest star visible to the naked eye?

Answer 1

This is a difficult question to answer because what star is visible to the naked eye depends on many factors:

1. Viewing conditions for that particular night (e.g. clouds, excess light)

2. Time of viewing (the earth moves so stars dip below the horizon as time passes)

3. The Earth's position in it's orbit around the Sun can make some stars harder to see.

So I'll answer your question based on the common constellations that are generally visible to most people from most places on Earth.

So take for instance the "asterism" The Big Dipper (Part of the Constellation Usra Major). It's one of the most famous and easily recognizable group of stars in the sky, and one of it's stars called "Dubhe" is 123.78 Light years away from us. That means the light from Dubhe takes 123yrs to reach us. In other words if Dubhe blew up we wouldn't know for 123yrs.

In the constellation "Orion" the star Alnilam is about 1359 Light years from us.

In Canis Major a star Aludra is about 3000 light years away.

So this is like a way of going back in time since you are seeing the star as it WAS in the past. These stars were not formed 3000yrs ago obviously. Some of the stars are 100's of millions of years old or more. You can check other constellations and their component stars to find out which are the farthest and the approximate time when they might have been formed. Many stars were formed BILLIONS of years ago after the big bang. Though it's hard to know how old a star is exactly we can guess it's approximate age based on it's metal content.

Of course using the logic above it's easy to say that our own Sun would be the oldest easily visible star.

Most stars are about 1Billion -10Billion years old

HE 1523-0901, is an estimated 13.2 billion years old, and is the oldest star discovered. It was one of the early stars to develop after the big bang. But this is not something you will see from your back yard on a clear night.