Alioth — Star in Ursa Major
HIP 62956; Epsilon Ursae Majoris; 77 Ursae Majoris
About Alioth
Description
Alioth is the brightest star in Ursa Major at magnitude 1.77, a chemically peculiar white star of spectral type A0pCr located about 83 light-years from Earth. It has a luminosity of roughly 102 times solar. Alioth is classified as an Alpha2 Canum Venaticorum variable — its brightness fluctuates very slightly due to starspots caused by an unusual concentration of chromium in patches on its surface.
Observing Tips
Alioth is the star nearest the bowl in the Big Dipper's handle — the brightest of the seven Dipper stars. It is circumpolar from mid-northern latitudes and visible year-round. It is a member of the Ursa Major Moving Group, sharing a common motion with most other Dipper stars. Best placed in the evening sky from March through August.
History
The name Alioth is of uncertain Arabic origin, possibly derived from 'alyat al-hamal' meaning 'the fat tail of the sheep.' It is one of the five Big Dipper stars that belong to the Ursa Major Moving Group — an association of stars with common space motion, suggesting they formed together.
Fun Facts
Alioth's surface has patches of concentrated chromium that create starspots, causing its brightness to vary very slightly as it rotates. This makes it the brightest member of the Alpha2 CVn class of magnetic chemically peculiar stars — stars where strong magnetic fields concentrate certain elements in patches.
Observe
1Physical Properties
2Position & Identifiers
3How easy to spot?
| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Easy | Easy | Easy |
| 50 mm finder 50mm finder | Easy | Easy | Easy |
| 150 mm telescope 150mm scope | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
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5Survey Image
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Explore
7
Size Comparison
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Compare Stars
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Spectral Classification
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Hertzsprung-Russell Diagram
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Stellar Lifecycle
12
Blackbody Spectrum
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Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
Discover
15Stellar Notes
16
Light Travel Time Machine
17
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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