Star Stars · In Auriga
Mahasim
Mahasim, θ Aurigae, is a white star in Auriga: the 108th brightest star in the night sky.
Save the chart (SVG) Tactile chart (A4 SVG)
- Constellation
- Auriga
- Designation
- θ Aurigae
- Apparent magnitude
- 2.65 · 108th brightest star in the night sky
- Spectral class
- A0p Si
- Distance
- 166 light-years
- Highest at midnight
- mid December
- Position (J2000)
- RA 06h 00m · Dec +37° 13′
A white star, around 10,000 K, like Sirius and Vega. About 35× brighter than the faintest star the eye can see. Gives off about 190 times the Sun's visible light. The light you are seeing left around 1860.
When to see it
On the night of Fri 18 Dec 2026, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | 13:22 | 00:11 · 76° | 11:00 |
| New York EST | 15:24 | 00:06 · 87° | 08:48 |
| Singapore GMT+8 | 19:13 | 01:16 · 54° | 07:20 |
| Sydney GMT+11 | 21:11 | 01:07 · 19° | 05:04 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 77° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 18° up in the north.
- When is the best time of year to see it?
- Around mid December, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid March it is highest in the early evening, and in mid September not until the hours before dawn.
- How far away is it, and how bright?
- It is 166 light-years away, and shines at magnitude 2.65 in our sky. From that far, the Sun would be a star of magnitude 8.3: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.65 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Menkalinan: Mahasim is 7.7° south of it, a fist at arm’s length.
Look for
From 50° north it climbs to 77°; from 35° north it climbs to 88°; from the equator it climbs to 53°; from 35° south it climbs to 18°.
Science
Mahasim’s surface is about 10,000 K, some 4,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 290 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 −0.9.
Did you know
Against Menkalinan, the brighter star the hop starts from: Menkalinan looks 2.0 times as bright as Mahasim in our sky, but Menkalinan is 81 light-years away and Mahasim 166 light-years, so side by side Mahasim would give off 2.1 times as much light as Menkalinan.
Science
Mahasim is the 77th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Elnath, about 43 light-years from it; on our sky the two are 11° apart.
Look for
The Sun passes 14° south of Mahasim around mid June, 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 21 hours a day, from 35° north about 16 and from 35° south about 8. It is 7° from the plane of the Milky Way, inside the band a dark sky shows.