Key Takeaways:
- Fomalhaut (Alpha Piscis Austrini), a magnitude 1.2 star, is visible in the southern sky after 8:30 PM local daylight time, reaching its highest point around midnight.
- Located 25 light-years from Earth, Fomalhaut is a young (450 million years old), relatively massive star (nearly 2 solar masses) with a diameter approximately 1.8 times that of the Sun.
- Fomalhaut possesses a large protoplanetary disk extending to five times Pluto's orbital distance, within which a previously suspected gas giant was later determined to be collisional debris.
- The provided text also includes sunrise, sunset, moonrise, moonset times, and moon phase for a specific location (40° N 90° W).
The bright star Fomalhaut stands prominently in the south late tonight, rising around 8:30 P.M. local daylight time. At magnitude 1.2, it outshines all other stars in this region. Fomalhaut is also cataloged as Alpha Piscis Austrini, the luminary of Piscis Austrinus the Southern Fish. It lies at the eastern end of this constellation, beneath larger Aquarius and to the lower left of Capricornus. According to Jim Kaler’s STARS website, the name Fomalhaut comes from Arabic and means “the mouth of the southern fish.”
Located just 25 light-years from Earth, Fomalhaut is a young star roughly 450 million years old. It weighs in at just under 2 solar masses and is about 1.8 times the width of the Sun. Fomalhaut is also famously surrounded by a large disk of dusty debris — this is a protoplanetary disk, from which a planetary system will someday form. The disk itself reaches out to some five times the orbit of Pluto (were it in our solar system).
Astronomers once thought they’d identified a gas giant planet within the disk; however, later observations showed the object was not actually a planet, but the debris left from a collision between forming planetesimals within the disk.
Fomalhaut is highest just after local midnight, when it stands about 20° above the southern horizon in the mid-U.S. Observers at lower latitudes will see it arc higher through the sky, and vice versa.
Sunrise: 6:35 A.M.
Sunset: 7:18 P.M.
Moonrise: 8:14 P.M.
Moonset: 8:45 A.M.
Moon Phase: Waning gibbous (95%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
For a look ahead at more upcoming sky events, check out our full Sky This Week column.
