Leo
What is Leo?
Constellations· Spring evenings (N) · the backwards question mark (Sickle). The signature of spring — the backwards question mark of the Sickle draws the head and mane, Regulus the heart. Also the radiant of November's Leonid meteors.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Leo is in your sky right now: https://nowsky.org/solar/sky?sel=con:Leo — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Regulus | 1.4 |
| Algieba | 2.0 |
| Denebola | 2.1 |
The 3 brightest of the 10 stars used in the figure (11 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | spring |
|---|---|
| Brightest star | Regulus (1.4) |
| Shape | the backwards-question-mark Sickle |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Leo?
- spring.
- What is the brightest star in Leo?
- Regulus, magnitude 1.4.
- In one line, what is Leo?
- Constellations — The signature of spring — the backwards question mark of the Sickle draws the head and mane, Regulus the heart.
- Where is Leo in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The lion's heart spins like a top
Regulus rotates once every 16 hours. Against the Sun's 25 days that is extreme, and centrifugal force swells its equator until the equatorial diameter is 32 percent larger than the polar one, close to the limit beyond which the star would fly apart. A star this flattened has an equator dimmer and cooler than its poles, so its measured brightness depends on the angle from which it is seen.
In 2008 a small companion, probably a white dwarf, was found circling Regulus every 40 days. The favoured explanation is that this companion once handed over mass and spun Regulus up to its present speed. The star set in the lion's heart on spring evenings is a single point to the eye, but in reality an ellipsoid turning at the edge of its limit, carrying rotation inherited from its partner.
The constellation in depth
Leo announces spring: the backwards question mark of the Sickle draws the head and mane, first-magnitude Regulus the heart — one of the few constellations that resembles its animal.
Regulus, 'the little king', sits almost exactly on the ecliptic, so the Moon and planets brush past it constantly and occasionally occult it.
Mid-November brings the Leonids, which erupt into storms on a ~33-year cycle — in 1833 tens of thousands of meteors an hour fell, 'the night the stars rained'. The next storm window: 2033–34.
Leo also lends its name to the Leonid meteor shower of mid-November, famous for 33-year storms — in 1833 tens of thousands of meteors per hour fell in the night 'the stars rained down.' Find the backwards question mark of the Sickle (the lion's head) in the spring evening sky and the body follows on its own.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.