Related topics: galaxies · stars · black holes · nasa · astronomers

Three new ultra-faint dwarf galaxies discovered

Using the Hubble Space Telescope (HST), astronomers have detected three new ultra-faint dwarf galaxies associated with the nearby spiral galaxy NGC 253. The newly found dwarfs turn out to be among the faintest systems so ...

Galaxy Haro 14 explored with MUSE

Using the Multi Unit Spectroscopic Explorer (MUSE), German astronomers have performed spectroscopic observations of a blue compact galaxy known as Haro 14. Results of the study, presented in a paper published August 20 on ...

Research investigates the brightest star of 47 Tucanae

Astronomers have inspected the brightest star of a globular cluster known as 47 Tucanae (other designation NGC 104). Results of the study, published August 3 on, provide important insights into the properties and ...

V404 Cygni: Huge rings around a black hole

This image features a spectacular set of rings around a black hole, captured using NASA's Chandra X-ray Observatory and Neil Gehrels Swift Observatory. The X-ray images of the giant rings reveal information about dust located ...

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A light-year or light year (symbol: ly) is a unit of length, equal to just under 1013 kilometres. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year.

The light-year is often used to measure distances to stars and other distances on a galactic scale, especially in non-specialist and popular science publications. The preferred unit in astrometry is the parsec, because it can be more easily derived from, and compared with, observational data. The parsec is defined as the distance at which an object will appear to move one arcsecond of parallax when the observer moves one astronomical unit perpendicular to the line of sight to the observer, and is equal to approximately 3.26 light-years.

The related unit of the light-month, roughly one-twelfth of a light-year, is also used occasionally for approximate measures.

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