Alpha Centauri

:This article is about the star system. For the computer game, see Sid Meier's Alpha Centauri.

Sky appearance from Alpha Centauri

Viewed from near Alpha Centauri, the sky (other than the Alpha Centauri stars) would appear very much as it does to observers on Earth, with most of the constellations such as Ursa Major and Orion being almost unchanged. However, Centaurus would be missing its brightest star and our Sun would appear as a 0.5-magnitude star in Cassiopeia. Roughly speaking, the // of Cassiopeia would become a ///, with the Sun at the leftmost end, closest to ε Cassiopeiae. The position can easily be plotted as RA 02h39m35s, dec +60°50', or antipodal to Alpha Centauri's position as seen from Earth.

Related Topics:
Ursa Major - Orion - Sun - Cassiopeia - ε Cassiopeiae - RA - Dec - Antipodal

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nearby very bright stars such as Sirius and Procyon would appear to be in very different positions, as would Altair to a lesser extent. Sirius would become part of the constellation of Orion, appearing to the west of Betelgeuse. The stars Fomalhaut and Vega, although further away, would appear somewhat displaced as well. Proxima Centauri would be an inconspicuous 4.5 magnitude star.

Related Topics:
Sirius - Procyon - Altair - Betelgeuse - Fomalhaut - Vega

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

A hypothetical planet around either ? Centauri A or B would see the other star as a very bright secondary. For example, an Earth-like planet at 1.25 Astronomical Units from ? Cen A (with a revolution period of 1.34 a) would get Sun-like illumination from its primary, and ? Cen B would appear 5.7 to 8.6 magnitudes dimmer (−21.0 to −18.2), 190 to 2700 times dimmer than ? Cen A but still 29 to 9 times brighter than the full Moon. Conversely, an Earth-like planet at 0.71 AUs from ? Cen B (with a revolution period of 0.63 a) would get Sun-like illumination from its primary, and ? Cen A would appear 4.6 to 7.3 magnitudes dimmer (−22.1 to −19.4), 70 to 840 times dimmer than ? Cen B but still 45 to 15 times brighter than the full Moon. In both cases the secondary sun would, in the course of the planet's year, appear to circle the sky. It would start off right beside the primary and end up, half a period later, opposite it in the sky (a "midnight sun"). After another half period, it would complete the cycle.

Related Topics:
Astronomical Unit - A

~ ~ ~ ~ ~ ~ ~ ~ ~ ~