- star brightness is measured on a scale of magnitude that was first devised in 150 BC by the ancient Greek astronomer Hipparchus.
Ancient Greek astronomer Hipparchus
Born: 190BC, Nicaea, Kingdom of Bithynia (Turkey)
Died: 120 BC (around age 70) Rhodes, Roman Republic (Greek Island)
- the brightest star that Hipparchus could see was Antares, and he described it as magnitude +1, he described the faintest star he could see as magnitude +6.
- using telescopes and binoculars, astronomers can now see much fainter stars than Hipparchus could.
- good binocular show magnitude 9+ stars, while a home telescope will show magnitude 10+ star.
- brighter star than Antares have been identified with magnitude of less than 1+, and even minus numbers. Betelgeuse is 0.5+, Vega is +0.03, and the Sun is -26.7.
- after the Sun, the brightest star visible from Earth is Sirius, the Dog Star, with magnitude of -1.46.
The brightest star visible from Earth is Sirius.
- the magnitude scale only describes how bright a star looks from Earth compared to other stars – this is its relative magnitude.
- the further away a star is, the dimmer it looks and the smaller its relative magnitude is, regardless of how bright it really is.
- a star’s absolute magnitude describes how bright a star actually is.
- the star Deneb is 60,000 times brighter than the Sun. However, as it is about 1800 light years, it looks dimer than Sirius.
Between Deneb star and our Sun.