What Is The Closest Star To Earth?
QUICK ANSWER
The closest star to Earth is the Sun, at about 93 million miles away. The next closest is Proxima Centauri, a red dwarf 4.24 light-years from Earth. Proxima Centauri is part of a triple-star system with Alpha Centauri A and B and has at least three known planets, including one in the habitable zone.
The Sun is technically the closest star to Earth, at just 93 million miles. After the Sun, the nearest star is Proxima Centauri, over 270,000 times farther away. The vast gap between the Sun and the next nearest star tells you something about how spread out stars are in the galaxy.
How close is the Sun?
About 93 million miles. According to NASA, that distance is staggeringly close compared to any other star. The Sun's proximity is what makes Earth habitable; it provides enough warmth and light for liquid water and complex life. The Sun is 270,000 times closer to Earth than the next nearest star. If the Sun were the size of a basketball, Proxima Centauri (the second closest star) would be the size of a peanut located 3,400 miles away. The gap between stars is enormous.
What's the closest star besides the Sun?
Proxima Centauri, at about 4.24 light-years away. The star is part of the Alpha Centauri triple-star system, which also includes Alpha Centauri A and Alpha Centauri B (a Sun-like pair). Proxima Centauri itself is a small, cool red dwarf about 12 percent of the Sun's mass and just 0.0017 percent of the Sun's brightness. It's too dim to see with the naked eye despite being our nearest stellar neighbor. Proxima Centauri is invisible from Earth without a telescope, even though it's the closest non-Sun star to us.
Does Proxima Centauri have planets?
Yes, at least three. The first confirmed planet, Proxima Centauri b, was announced in 2016. It's roughly Earth-sized and orbits in its star's habitable zone, where liquid water could potentially exist on the surface. Two more planets (Proxima c and Proxima d) have since been confirmed. Whether any of these are actually habitable is uncertain. Red dwarf stars often produce strong stellar flares that can strip away planetary atmospheres, and Proxima Centauri is known to be unusually active. Still, Proxima b is one of the most studied exoplanets because of its proximity.
How long would it take to reach Proxima Centauri?
Tens of thousands of years with current technology. Even moving at the speed of NASA's Voyager 1 (about 38,000 mph), reaching Proxima Centauri would take about 75,000 years. The fastest spacecraft we have built would still take roughly 6,000 years. The Breakthrough Starshot project has proposed using lasers to accelerate tiny spacecraft to 20% of the speed of light, which would reach Proxima Centauri in about 22 years, but the technology is still in early development.
The closest star to Earth is the Sun, at 93 million miles. The next closest is Proxima Centauri, over 270,000 times farther away at 4.24 light-years. Proxima Centauri has three known planets, including one in its habitable zone, making it a target for astronomers studying potential life beyond our solar system. The vast gap between the Sun and any other star is a reminder of how isolated our solar system really is.
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