What is the closest star to planet Earth? Many people will mention Alpha Centauri. But the closest star to Earth is our Sun! The nearest known star to our solar system is Alpha Centauri-C (sometimes called "Proxima Centauri") in the Alpha Centauri system. This system contains three stars. Alpha Centauri (depicted in the above image) is a close binary star consisting of Alpha Centauri A and Alpha Centauri B. They appear as a single star to the unaided eye, but resolve into a double star in a telescope using higher power. They orbit around a common center of mass in 79 years, and are separated by 40 "astronomical units" (the average distance between the Sun and Earth)--a distance comparable to that separating the Sun and Pluto. Alpha Centauri A is almost identical to our Sun in size, mass, and stellar classification (G2). A distant third member of this system is Proxima (Latin for "nearest"), which is separated from the A and B stars by 13,000 astronomical units. Proxima's distance, as measured by stellar parallax (geometric triangulation) is 4.24 light years, or some 25 trillion miles, making it the closest known star to our Sun. Alpha Centauri A and B are 4.366 light years from the Sun.
It is difficult to comprehend 4.24 light years. This may help. The fastest interstellar spacecraft man has constructed (Voyager 1), traveling at 1 million miles per day, would take 84,000 years to reach Proxima, the closest star in the universe to our solar system.
Alpha Centauri (A and B) is the brightest "star" in the southern constellation Centaurus, and with a visual magnitude of -0.27 is the third brightest star in the sky. Only Sirius and Canopus are brighter. It is located in a star rich region of the Milky Way, which is readily observed in the above image. The brownish region is a veritable infinitude of stars in the direction of the galactic center. The black areas are massive clouds of obscuring dust.
Alpha Centauri is located high in the southern sky, and is only visible in North America below latitude 29 North (i.e., Houston Texas, the Flordia Keys--where it rises a few degrees above the southern horizon). Our solar system's closest stellar neighbor is not visible in most of North America.
Alpha Centauri--the nearest star (after the Sun)
Date Taken:March 13, 2014
Location Taken:Siding Spring Observatory, NSW Australia
Conditions of Location: Equipment Used:Takahashi FSQ106 refractor and SBIG STL11000 camera
Processing Used:8x2 minute images using clear, red, green, and blue filters for a total exposure of 64 minutes, processed in Maxim DL and Photoshop
Distance from Location:4.24 light years
Constellation:Centaurus
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