Glossary term: Light-Year

Description: A light-year is a large unit of length used by astronomers to express large astronomical distances like distances to stars or between galaxies. It is defined as the distance that light travels in vakuum in one year: 9.46 trillion kilometers, that is 9.5 10 12km. By using the unit light year the large distances become numerically more manageable: our nearest star is 40 trillion km away or more simply 4.25 light years. Astronomers also use the units light-minutes or light-hours: Light takes about 8 minutes to get from the Sun to Earth and about 4 hours and 9 minutes to get to Neptune.

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Term and definition status: This term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".