Key facts
- Category
- Stars
- Object class
- K-type orange giant star
- Mass
- ~1.1 solar masses
- Temperature
- ~4,300 K surface
- Scale fact
- 35 million kmdiameter
- Estimated age
- ~7.1 billion years
- Composition
- Hydrogen and helium
Arcturus
35 million kmdiameter
Visual creditscaleofspace.org / CC BY-NC 4.0
Details
Arcturus is a bright orange giant and the brightest star in the northern celestial hemisphere. It also races unusually fast across the sky for such a bright star, shifting by about two arcseconds per year because of its high motion relative to the Sun.
Arcturus is an orange giant with roughly the Sun’s mass but about 25 times its diameter. It has exhausted the hydrogen in its core and expanded, giving it a cooler surface than the Sun while producing far more total light.
Its proper motion is unusually large for such a bright naked-eye star: its position shifts by about two arcseconds each year. Spectroscopic measurements also show a high velocity relative to the Sun, tracing a different path through the Milky Way from most nearby disk stars.
Links
- Editorial guides
- Universe journey
- Solar neighborhood
- Preset views
- Wikipedia
- Arcturus on Wikipedia
Size neighbors
Objects near Arcturus on the scale
On the logarithmic size axis, Arcturus falls between Sagittarius A* and Aldebaran. The band uses nearby K-type orange giant star records.
Sources
References for Arcturus
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Arcturus — Wikipedia
- Visual: scaleofspace.org / CC BY-NC 4.0
Continue with nearby objects or open the full scale.
About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.