Explanation:
Located just next door,
Alpha Centauri is the closest star system to the Sun.
A view from our
interstellar neighbor
a mere 4.3 light-years away is shown in this illustration.
The Sun is at
the upper right, a bright star against the background of the Milky Way.
The crescent in the foreground is an artist's rendering of a planet
now reported orbiting
Alpha Centauri B, making it the closest
known exoplanet.
Discovered by astronomer
Xavier Dumusque et al. using the
planet hunting HARPS
instrument to measure minute shifts in the star's spectrum for
more than four years, the planet has approximately the same mass as Earth.
But it orbits once every 3.2 days, about 0.04 times the Earth-Sun distance
from its parent star.
That puts it well outside
the habitable zone,
much too close to Alpha Cen B, a star only a little cooler
than the Sun.
Still, estimates indicate that planetary orbits would be stable
within the habitable zone of Alpha Cen B, at about half the Earth-Sun
distance ...
