# Hamal (Alpha Arietis)

Hamal (Alpha Arietis) is a star in the constellation Aries, magnitude 2.0.

**The Ram’s head — the reason horoscopes still begin with Aries.**

Why do horoscope columns start with Aries? Between about 2000 and 100 BC the Sun stood in this constellation at the March equinox, the start of northern spring. Hamal, its brightest star, shone near what was then a key point in the sky. Precession has since moved the equinox into Pisces, but the habit stuck.

The name comes from the Arabic for “head of the ram”. It is an orange giant that has used up the hydrogen in its core: about 1.4 times the Sun’s mass, some 15 times wider and 91 times as luminous. Since 1943 its spectrum has been one of the fixed reference points astronomers use to classify other stars.

In 2011 a team led by Byeong-Cheol Lee in South Korea reported a likely [planet](https://astropilot.space/glossary/planet) circling it every 381 days, at least 1.8 times the mass of Jupiter. Its orbit would take it a little farther from Hamal than Earth is from the Sun.

Hamal (Alpha Arietis) is 66 light-years away: the light we see from it set off in 1960, 3 years after Sputnik became the first artificial satellite.

## Did you know?

- **A world in a novel.** James Blish’s 1953 novel A Case of Conscience is set largely on Lithia, an imaginary planet of Hamal that is home to an alien race.
- **Overhead on the Tropic.** Hamal’s declination is almost exactly the latitude of the Tropic of Cancer, so seen from that line on Earth it passes straight overhead.
- **Chaucer’s name for it.** Geoffrey Chaucer knew it as Alnath, Arabic for “the butting horns”. That name has since moved to Beta Tauri, now called Elnath.

The brightest star of Aries: an orange 2nd-magnitude star that, with white Sheratan and fainter Mesarthim, makes the Ram’s short, bent head. Find it between the Pleiades and the Great Square of Pegasus; binoculars show its orange beside Sheratan’s white.

## When and where to see it

It is best placed in the evening sky around November, when it crosses the meridian at about 10 pm local time (around midnight in October). It can be seen from everywhere north of 67°S and never sets north of 67°N.

At its highest it stands 63° up from 50°N, 78° up from 35°N, 67° up from the equator, 32° up from 35°S.

## Facts

- Type: Star
- Constellation: Aries
- Designations: Alpha Arietis, α Ari, 13 Ari, HR 617, HD 12929, HIP 9884
- Magnitude: 2.0
- Position: RA 2h 7.2m, Dec +23° 28′ (J2000)
- Spectral type: K2-IIIbCa-1
- Colour: orange (B−V 1.16)
- Distance: 66 light-years
- Discovered: Known since antiquity

Open AstroPilot to see when Hamal (Alpha Arietis) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/hamal