How Far are Stars?

All the stars in the Milky Way galaxy (which contains our Sun, Earth and the other planets) are millions of miles away from the Earth. On clear nights, when there isn’t a lot of man-made light to interfere it seems that the stars are very close. The Sun, which is also a star, is relatively close to the Earth. It provides the light and heat that makes it possible for living things to exist on the planet.

But the truth is, the stars are so far from the Earth that we could not travel to the closest of them and be alive when we arrived. The Sun is about 93 million miles away and it is the closest star. The closest among the other stars is millions of miles from Earth.

When we think of it from our viewpoint on Earth, the distance is almost unimaginable. The stars are quite simply very, very far from us. In the last few decades, the stars have become “closer” in a way. Human beings have been able build rockets, satellites and orbiting cameras that have allowed us to get a much closer look at the stars. We have been able to get better estimates of the number of stars in our galaxy and in the other galaxies that make up what we know as the universe.

Technology has made it possible to know much more about what stars are made of, what makes them “shine” in the night sky and why some seem to be so much larger and brighter than others. We get a more realistic idea of what our sky is when we can visualize the stars as being scattered at many different distances from the surface of the planet. Though the distance is so great it seems that the night sky is a flat, dark surface dotted with small lights, the stars are actually widely separated at different distances.

Human beings began devising ways to estimate the distance of different stars hundreds of years ago. One method involves measuring the amount of light that reaches the earth from at least two different locations. Unfortunately for the scientists trying to make accurate measurements, it’s impossible to get far enough apart on Earth to make this type of measurement. Measurement from two locations as far from each other as possible on Earth still do not give us two noticeable differences in distance.

Astronomers then tried observing and measuring at different times. The length of the Earth’s orbit around the Sun does give scientists enough distance to come up with at least two measurements, the average of which is more accurate than one measurement would be. With this method scientists have found that the closest star is much farther from Earth than the Sun, which is about 93 millions miles away. Light from this nearest star (apart from the Sun) takes about four years to travel to Earth at the speed of light. The light we see tonight began its trip from the star four years ago