Stellar parallax

Imagine you are sitting in the backseat of a car and looking out of the window. You see some objects that are close to the road, like trees or lampposts, seem to move faster than objects that are far away, like buildings or mountains. This happens because the closer objects are moving quickly past you, while the far away objects are moving more slowly, giving you the impression that they are not moving at all.

The same idea applies to stars in space! Astronomers use a technique called “stellar parallax” to measure how far away stars are. They look at the position of a star in the sky at different times of the year, when the Earth is on the opposite sides of the Sun. If a star is close to us, its position will appear to move more relative to background stars than if it is far away. This is because the closer star has a bigger "parallax angle," meaning the difference in its position when viewed from two different points (in this case, Earth’s position in space).

Think of it like playing a game of 'peek-a-boo.' You are the observer, and the star is the person you are playing with. When you look at the star from Earth's 'hide' position, it will be in one position. Then, as Earth 'peeks' over to the other side of the sun, you look at the star from that new position, and it seems to change slightly in position. This technique allows astronomers to determine how far away the star is!

By measuring the parallax angle of a star, astronomers can calculate the distance of the star from Earth. This is helpful in making maps of our galaxy and knowing more about the Universe we live in!