Star Stars · In Leo
Zosma
Zosma, δ Leonis, is a white main-sequence star in Leo: the 99th brightest star in the night sky.
Save the chart (SVG) Tactile chart (A4 SVG)
- Constellation
- Leo
- Designation
- δ Leonis
- Apparent magnitude
- 2.56 · 99th brightest star in the night sky
- Spectral class
- A4V
- Distance
- 58.4 light-years
- Highest at midnight
- early March
- Position (J2000)
- RA 11h 14m · Dec +20° 31′
A white main-sequence star, around 9,000 K, like Sirius and Vega. About 38× brighter than the faintest star the eye can see. Gives off about 25 times the Sun's visible light. The light you are seeing left in 1968.
When to see it
On the night of Mon 8 Mar 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | 16:20 | 00:10 · 59° | 08:00 |
| New York EST | 16:51 | 00:04 · 70° | 07:18 |
| Singapore GMT+8 | 19:14 | 01:15 · 71° | 07:16 |
| Sydney GMT+11 | 20:05 | 01:06 · 36° | 06:07 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 61° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 34° up in the north.
- When is the best time of year to see it?
- Around early March, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early June it is highest in the early evening, and in early December not until the hours before dawn.
- How far away is it, and how bright?
- It is 58.4 light-years away, and shines at magnitude 2.56 in our sky. From that far, the Sun would be a star of magnitude 6.1: one you would need a dark country sky to see at all.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.56 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Denebola: Zosma is 10° north-west of it, a fist at arm’s length.
Look for
From 50° north it climbs to 61°; from 35° north it climbs to 76°; from the equator it climbs to 69°; from 35° south it climbs to 34°.
Science
Zosma’s surface is about 9,000 K, some 3,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 320 nm, in the ultraviolet, past the violet end of what the eye can see, where the Sun’s is strongest at 500 nm. Moved to 33 light-years, the distance astronomers compare stars at, it would shine at magnitude 1.3, about as bright as Mimosa looks to us.
Did you know
Against Denebola, the brighter star the hop starts from: Denebola looks 1.5 times as bright as Zosma in our sky, but Denebola is 36 light-years away and Zosma 58 light-years, so side by side Zosma would give off 1.8 times as much light as Denebola.
Science
Zosma is the 20th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Denebola, about 24 light-years from it; on our sky the two are 10° apart.
Look for
The Sun passes 14° south of Zosma around early September, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 50° north it is above the horizon for about 15 hours a day, from 35° north about 14 and from 35° south about 10. It is 67° from the plane of the Milky Way, well away from the band.