# Denebola (Beta Leonis)

Denebola (Beta Leonis) is a star in the constellation Leo, magnitude 2.1.

**The Lion’s tail — a young, fast-spinning white star ringed by a disc of cold dust.**

Denebola is short for Deneb Alased, Arabic for “tail of the lion”. Medieval writers linked it with the weather: Ulugh Beg called it al-Ṣarfah, “the Changer”, and al-Biruni wrote that its rising ends the heat and its setting ends the cold.

It is a young white [star](https://astropilot.space/glossary/star), less than 400 million years old, with 75 per cent more mass than the Sun and 15 times its luminosity. It spins fast — about 128 km per second at its equator, against the Sun’s 2 — enough to squash it into a flattened ball. It also flickers very slightly, about ten times a day, as a Delta Scuti [variable star](https://astropilot.space/glossary/variable-star).

Around it orbits a disc of cold dust at about −153 °C, lying roughly as far from the star as Pluto is from the Sun; the Herschel Space Observatory imaged it. Our own Solar System formed from such a disc, so Denebola, like Vega, is a place where planets might be found.

Denebola (Beta Leonis) is 36 light-years away: the light we see from it set off in 1990, around the time the Hubble Space Telescope was launched.

## Did you know?

- **A scattered family.** Denebola shares its motion through space with more than sixty stars, including the open cluster IC 2391. They may once have been born together.
- **Seat of the Five Emperors.** Ancient Chinese astronomers made it the first star of the “Seat of the Five Emperors”, a five-star asterism.

A white 2nd-magnitude star at the tip of Leo’s tail, the eastern point of the triangle of stars that forms the Lion’s hindquarters. With Arcturus and Spica it makes a large, nearly equal-sided triangle.

## When and where to see it

It is best placed in the evening sky around April, when it crosses the meridian at about 10 pm local time (around midnight in March). It can be seen from everywhere north of 75°S and never sets north of 75°N.

At its highest it stands 55° up from 50°N, 70° up from 35°N, 75° up from the equator, 40° up from 35°S.

## Facts

- Type: Star
- Constellation: Leo
- Designations: Beta Leonis, β Leo, 94 Leo, HR 4534, HD 102647, HIP 57632
- Magnitude: 2.1
- Position: RA 11h 49.1m, Dec +14° 34′ (J2000)
- Spectral type: A3Va
- Colour: white (B−V 0.09)
- Distance: 36 light-years
- Discovered: Known since antiquity

Open AstroPilot to see when Denebola (Beta Leonis) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/denebola