Constellation, Leo
Leo: the Lion
Leo covers 944 square degrees of sky, the 12th largest of the 88. Its brightest star is Regulus. It is best placed in the evening sky in April.
Leo at a glance
| Fact | Value |
|---|---|
| IAU abbreviation | Leo |
| Meaning | the Lion |
| Pronounced | LEE-oh |
| Genitive, used in star names | Leonis (for example a Bayer name such as α Leonis) |
| Area | 944 square degrees, number 12 of 88 by size |
| Stars to magnitude 6 in our catalogue | 80 |
| Brightest star | Regulus, magnitude 1.4 |
| Best seen | Evenings in April, when it is highest at 9 pm |
| Declination range | -7° to 33° |
| Borders | Leo Minor, Sextans, Virgo, Cancer, Coma Berenices, Ursa Major, Crater, Hydra, Lynx |
Where on Earth you can see Leo
Leo spans declinations -7° to 33°. Every part of it rises above the horizon at some moment for observers between latitudes 57°S and 83°N. Some of it can be seen from every latitude. This is geometry only: it ignores haze, hills and buildings near the horizon.
From six cities
| City | Latitude | Visibility | Middle at its highest |
|---|---|---|---|
| Pune | 18.5°N | All of it rises | 86° |
| New York | 40.7°N | All of it rises | 63° |
| London | 51.5°N | All of it rises | 53° |
| Tromsø | 69.6°N | All of it rises | 34° |
| Tokyo | 35.7°N | All of it rises | 68° |
| Sydney | 33.9°S | All of it rises | 42° |
Leo's named stars
These stars in Leo have names approved by the IAU Working Group on Star Names. Magnitude is brightness: a lower number is brighter, and the faintest stars seen with the naked eye on a dark night are about magnitude 6.
| Star | Designation | Magnitude | Distance (light-years) |
|---|---|---|---|
| Regulus | α Leonis | 1.36 | 79.3 |
| Algieba | γ1 Leonis | 2.01 | 130 |
| Denebola | β Leonis | 2.14 | 35.9 |
| Zosma | δ Leonis | 2.56 | 58.4 |
| Chertan | θ Leonis | 3.33 | 170 |
| Adhafera | ζ Leonis | 3.43 | 270 |
| Subra | ο Leonis | 3.52 | 130 |
| Rasalas | μ Leonis | 3.88 | 120 |
| Alterf | λ Leonis | 4.32 | 330 |
Distances are about, from the HYG database (Hipparcos parallax), and "not known" means the catalogue has no reliable parallax for that star.
How these facts were found
The name, meaning and boundaries are the IAU's. Area, borders and the latitude ranges are computed from those boundaries; the brightest star and the star count come from a magnitude-6 star catalogue; star names are matched to the catalogue by Hipparcos number and checked by position. The month is when Leo's middle crosses the north-south line of the sky at 9 pm local solar time. See How we know.
Sources
- IAU: The Constellations. Names, meanings, pronunciations and boundaries
- IAU Working Group on Star Names. The official names of stars
- astronomy-engine. The MIT licensed library that does the calculations, run on the page's build machine and in the app
- HYG database v4.4 (astronexus). Distances, spectral types and luminosities, licence CC BY-SA 4.0