How do we determine the distance to nearby stars?

We determine the distance to nearby stars using parallax.

Parallax is the apparent shift in the position of an object when viewed from different angles. To measure the parallax of a star, astronomers observe its position in the sky from two different points in Earth's orbit, six months apart. By measuring the angle between the two observations, astronomers can calculate the star's distance using trigonometry.

However, the parallax method can only be used for stars within a certain range. The further away a star is, the smaller its parallax angle becomes, making it more difficult to measure accurately. Therefore, the parallax method is only reliable for stars within a few hundred light-years of Earth.

For stars beyond this range, other methods are used, such as the distance modulus method. This method uses the star's apparent brightness and its known absolute brightness to calculate its distance. However, this method relies on assumptions about the star's luminosity and can be less accurate than the parallax method.

Overall, determining the distance to nearby stars is a crucial part of understanding the structure and evolution of our galaxy. The parallax method remains the most reliable and accurate method for measuring distances to nearby stars.