The constellations are at a distance of hundreds or thousands of light years from each other. The constellations are formed by several stars and as they are not in a plane, each star is at a different distance from a fixed point, so belong to the same constellation.
The nearest star to the Sun is Alpha Centauri, which is at a distance of 4.37 light years, equivalent to 41.3 billion kilometers.
Alpha Centauri belongs to the Centauri constellation, which is formed by a system of 3 stars gravitationally united: Alpa Centauri; Alpa Centauri B and Next Centauri.
One of the most well-known constellations is Orion. In Orion are several of the brightest stars seen from the earth. These stars are at a distance ranging from 243 to 1360 light years.
The brightest star of Orion is Rigel, which has a brightness 51000 times more powerful than the Sun, and is 777 light-years away.
For its part, the nearest star is Bellatrix, which is 243 light years and 6000 times brighter than the Sun.
Almost all stars in the constellations are within a radius of no more than 1000 light years between them.
Organization of the constellations in the sky
In the modern era the galaxy is organized into 88 constellations, the area they cover in the sky is measured in square degrees.
Eugène Delporte was the one who drew the boundaries with horizontal and vertical imaginary lines using as reference to the land in 1875.
The definitive boundaries between the constellations were fixed in 1930 by the International Astronomical Union, that is, as each star is within the confines of a constellation .
Astronomers study more clearly defined areas in the sky than the stars that make up the stars.
Ways of measuring distances in the sky
The space is so large that it tends to be infinite by this it becomes almost impossible to measure it in miles or kilometers. This has led to special systems to measure the distances of the universe.
The metric systems used to calculate distances in the universe are:
- Astronomical unit (water). Average distance between the Earth and the Sun. 149.600.000 km.
- Light-year. Distance that travels light in a year. 9.46 trillion km or 63,235.3 reals.
- Parsec (parallax). Distance of a body having a parallax of 2 arc segments. 30.86 billion km, 3.26 light years or 206,265 water.
The astronomical unit is only used to measure the distances between the Sun and Earth. It is not used outside our solar system.
For its part, the speed of light is calculated at the rate of 300,000 kilometers per second and in parallax is measured the angle that forms between the star and the Earth in the two opposite points of its orbit around the Sun.
References
- Payne Nick (2012) Constellations. London, UK: Faber & Faber.
- Delporte Eugéne (1930) Délimitation scientifique des constellations (tables et cartes). Cambridge, UK: At University Press.
- Bakich Michael (1995) The Cambridge Guide to the Constellations. Cambridge, UK: AT University Press
- Constellation Guide (2017) The University of Texas McDonald Observatory retrieved from stardate.org
- Welcome to the Sun's Neighborhood (2014) Jet Propulsion Laboratory retrieved from nasa.gov.