What is a light-year and how is it used?? - NASA
Question: What is a light-year and how is it used? Answer: 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 trillion km. More p recisely, one light-year is equal to 9,500,000,000,000 kilometers ...
StarChild: Glossary - NASA
LIGHT YEAR The distance light can travel in one year, which is 9,500,000,000,000 kilometers. M MAGNETIC FIELD The area in which an attractive or repelling force exists between two magnets or in association with the element iron. The Earth's magnetic field is thought to be due to the liquid iron-nickel which is in its core.
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. The star outside of our solar system that is closest to Earth is Alpha Centauri C.
StarChild: Galaxies - NASA
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 as a million light-years across.
Redshift and Hubble's Law - NASA
Redshift and Hubble's Law. For very far objects (beyond about 1 billion light-years) none of the above methods work. Scientists must move from direct observation to using observations in conjunction with a theory. The theory used to determine these very great distances in the universe is based on the discovery by Edwin Hubble that the universe ...
Parallax - NASA
Parallax. Parallax. Astronomers derive distances to the nearest stars (closer than about 100 light-years) by a method called stellar parallax. This method that relies on no assumptions other than the geometry of the Earth's orbit around the Sun. You are probably familiar with the phenomenon known as parallax.
Cepheids - NASA
Cepheids. 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 of light-years. In 1912, Henrietta Swan Leavitt noted that 25 stars, called Cepheid stars, in the Magellanic cloud would brighten and dim periodically.
How do we measure the distances to things in space? - NASA
But all of the methods are wonderful combinations of science and mathematics! The links below will take you to descriptions of various common methods. Radar - measuring distances in our solar system. Parallax - measuring distances to nearby stars. Cepheids - measuring distances in our Galaxy and to nearby galaxies.
Where do comets come from? - NASA
Comets are believed to have two sources. Long-period comets (those which take more than 200 years to complete an orbit around the Sun) originate from the Oort Cloud. Short-period comets (those which take less than 200 years to complete an orbit around the Sun) originate from the Kuiper Belt. Danish astronomer Jan Oort proposed that comets ...
StarChild: Glossary - NASA
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 ROVER The car-like vehicle used by Apollo astronauts while exploring the Moon's surface. M MASS The amount of matter in an object. MATTER What all things are made of ...