COSMOS / CONSTELLATIONS / LEO
Leo (Lion)
The Lion. IAU abbreviation Leo. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Leo
- Latin name / genitive
- Leo / Leonis
- Position
- Right ascension ≈ 10 h 40 m; declination −5° to +31°
- Visibility from Türkiye
- Visible in full from anywhere in Türkiye. When it crosses the meridian its centre stands about 63° above the horizon from Ankara.
- Best time to observe
- Best placed at 21:00 Türkiye time around 29 April.
- Number of stars
- 128 stars brighter than magnitude 6.5 in the catalogue; 32 brighter than 5 and 12 brighter than 4.
INTERACTIVE LAB
Where is Leo tonight?
The lab opens for Ankara on today’s date. Drag the time slider through the night; the “Best night” button jumps to the date when the constellation is highest at 21:00 (around 29 April). Change the city to compare the view from elsewhere in Türkiye and around the world.
MYTH, HISTORY AND OBSERVING
The Nemean lion slain by Heracles as his first labour; one of the most recognisable constellations of the zodiac. Regulus, lying almost on the ecliptic, is occasionally occulted by the Moon and planets; the stars outlining the lion’s head are called the “Sickle”. The mid-November Leonid meteor shower and the Leo Triplet of galaxies (M65, M66, NGC 3628) belong here.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| Regulus | 1.36 | 79 | B7V |
| Algieba | 2.01 | 130 | K0III |
| Denebola | 2.14 | 36 | A3Vvar |
| Zosma | 2.56 | 58 | A4V |
| Ras Elased Australis | 2.97 | 247 | G0II |
| Chertan | 3.33 | 165 | A2V |
| Adhafera | 3.43 | 274 | F0III |
| η Leo | 3.48 | 1,269 | A0Ib |
Magnitude: apparent brightness; the smaller the number, the brighter the star. Distances derive from parallax measurements and are uncertain for distant stars. Source: HYG v4.1 star catalogue (CC BY-SA 4.0).
SOURCES
Position, visibility and best observing time were computed approximately for this page from the catalogue stars (Ankara, 39.9° N). The 88 constellations were adopted by the IAU in 1922; their boundaries were drawn by Eugène Delporte in 1930.