What is a light-year and how is it used?? - NASA
A light-year is a unit of distance. It is the distance that light can travel in one year. Light moves at a velocity of about 300,000 kilometers (km) each second. So in one year, it can travel about 10 …
Just How Big is this Place - NASA
A light year is equal to 9,500,000,000,000 km and is the distance that light travels in one year. A light year can be expressed as 9.5 trillion km or in scientific notation as 9.5 x 10 12 km.
Does the Sun move around the Milky Way?? - NASA
Yes, the Sun - in fact, our whole solar system - orbits around the center of the Milky Way Galaxy. We are moving at an average velocity of 828,000 km/hr. But even at that high rate, it still takes …
StarChild: Galaxies - NASA
Wow! A light-year is 9.5 trillion kilometers and is the distance light travels in one year. Galaxies range from a few thousand to a million light-years in diameter. A galaxy is a cluster of stars, …
StarChild: The Milky Way - NASA
Our Sun is a star in the Milky Way Galaxy. If you were looking down on the Milky Way, it would look like a large pinwheel rotating in space. Our Galaxy is a spiral galaxy that formed …
Cepheids - NASA
Cepheids, also called Cepheid Variables, are stars which brigthen and dim periodically. This behavior allows them to be used as cosmic yardsticks out to distances of a few tens of millions …
Supernovae - NASA
Supernovae At large distances (up to about 1 billion light-years), astronomers can no longer use methods such as parallax or Cepheid variables. At such large distances, the parallax shift …
StarChild: Galaxies - NASA
Galaxies A light-year is the distance light travels in one year. It is 9.5 trillion (9,500,000,000,000) kilometers. The size of a galaxy may be as little as a thousand light-years across or as much …
What is the biggest star we know? - NASA
StarChild Question of the Month for May 2000 Question: What is the biggest star we know? Answer: The largest known star (in terms of mass and brightness) is called the Pistol Star. It is …
StarChild: Glossary - NASA
L LIGHT YEAR The distance light can travel in one year, which is 9,500,000,000,000 kilometers. LUNAR MODULE The section of the Apollo spacecraft designed to land on the Moon. LUNAR …