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Yes, ”what is the closest star to Earth” is a trick question. Our Sun is by far the closest star to us. So, all games aside, let’s look at the stars outside of our solar system that are closest to Earth.
The closest star to our Sun would be one of the three in the Alpha Centauri system. The system is only 4.27 light years from the Sun. Alpha Centauri A is the primary in the system. It is slightly larger than our Sun. It has a similar yellowish color with a stellar classification of spectral type G2 V. It also rotates every 22 days compared to 25 for the Sun. The secondary, Alpha Centauri B, is slightly smaller and has a spectral type of K1 V. It is orangish-yellow compared to the primary. It is 90% as massive as our Sun and about 14% smaller in radius. It rotates every 41 days. The third in the system is called Proxima Centauri. It would technically, be the closest single star to our Sun at 4.22 light years.
After you move past the Alpha Centauri group, the next closest star to Earth, 4th closest overall, would be Barnard’s Star. This a spectral type M4 Ve star that is about 6 light years from the Sun and is located in the constellation Ophiuchus. It has received more hours of study than any other M class star because of its proximity. E.E Barnard discovered the star and measured its proper motion at 10.3 arcseconds per year. To date, this is the largest known proper motion of any star in relation to our Sun.
Next we move to Wolf 359. This star falls in the spectral type M6.5 Ve and is located in the Leo constellation. It is around 7.6 light years from the Sun. It is one of the faintest and lowest mass stars known. Absorption lines showing the presence of water and titanium have been observed in the star’s spectrum. It has a stronger magnetic field than our Sun, so it can undergo sudden increases in luminosity lasting for several minutes.
Those are the five stars closest to the Sun. Here are the next five:
- Epsilon Eridani
- 61 Cygni
- Tau Ceti
- Kruger 60
According to NASA data, there are 45 stars within 17 light years of the Sun. There are thought to be as many as 200 billion stars in our galaxy. Some are so faint that they are nearly impossible to detect. Maybe, with technological improvements, scientists will find even closer stars.
We’ve also recorded an episode of Astronomy Cast all about the Sun. Listen here, Episode 30: The Sun, Spots and All.