# Mirfak (Alpha Persei)

Mirfak (Alpha Persei) is a star in the constellation Perseus, magnitude 1.8.

**The heart of Perseus — a yellow-white supergiant shining from the middle of its own star cluster.**

Mirfak is a supergiant [star](https://astropilot.space/glossary/star) in the later stages of its life, six to seven times the Sun’s mass and swollen to about 54 times its width. It shines with some 4,000 times the Sun’s light from a surface at about 6,400 K, a yellow-white glow. Its spectrum looks much like Procyon’s, yet it is far more luminous. The Yerkes system of 1943, which ranks stars by luminosity as well as type, tells the two apart, and Mirfak has been one of its reference stars ever since.

It sits in the zone of temperature and brightness where pulsing Cepheid variables live, so it helps astronomers understand them — though Mirfak itself barely flickers. A suspected giant planet was ruled out in 2025: the wobble it seemed to cause kept changing, and is more likely the star’s own oscillations.

Its name is Arabic for ‘elbow’, from mirfaq al-thurayyā, ‘the elbow of the Pleiades’.

Mirfak (Alpha Persei) is 510 light-years away: the light we see from it set off around 1515, 25 years after Columbus crossed the Atlantic.

## Did you know?

- **Hinaliʻi.** In Native Hawaiian astronomy Mirfak is Hinaliʻi. The name commemorates a great tsunami and marks the beginning of the migration of Maui.
- **The Celestial Boat.** Chinese astronomers made Mirfak the third star of Tiān Chuán, the Celestial Boat, a pattern made from stars of Perseus.

A yellow-white star, the brightest in Perseus, outshining famous Algol nearby. Turn binoculars on it: it sits among a sparkling scatter of blue-white stars, the Alpha Persei Cluster.

## When and where to see it

It is best placed in the evening sky around December, when it crosses the meridian at about 10 pm local time (around midnight in November). It can be seen from everywhere north of 40°S and never sets north of 40°N.

At its highest it stands 90° up from 50°N, 75° up from 35°N, 40° up from the equator, 5° up from 35°S.

## Facts

- Type: Star
- Constellation: Perseus
- Designations: Alpha Persei, α Per, 33 Per, HR 1017, HD 20902, HIP 15863
- Magnitude: 1.8
- Position: RA 3h 24.3m, Dec +49° 52′ (J2000)
- Spectral type: F5Ib
- Colour: yellow (B−V 0.48)
- Distance: 510 light-years
- Discovered: Known since antiquity

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