Deep Southern Skies #299
Mercury at its best in the evening sky.
Mercury, Moon and Spica form a triangle (26th).
Saturn and the crescent Moon close twice this month.
Comet PANSTARRS well placed in the morning sky
2nd First Quarter.
8th Moon at perigee (closest vto Earth at 358,389 km).
9th Full Moon.
16th Last Quarter.
20th Moon at apogee (farthest from Earth at 405,845 km).
Mercury in Virgo the entire month, is at its best in the western evening sky. On the 20th and 31st the innermost planet will be less than 1° from the 1st magnitude star Spica (Alpha Virginis). On the 26th, an attractive display occurs when the slender crescent 2-day old Moon joins Mercury and Spica, forming a triangle.
Venus is visible in the morning twilight in the first week of September. On the 6th, Venus will be just 0.7° from the 1st magnitude star Regulus, the brightest star in Leo in the twilight close to the horizon. It will then disappear from view and will reappear in the early December evening dusk as the Evening Star.
The Earth is at its vernal (spring) equinox on the 23rd. An observer on the equator will see the Sun rise due east and set due west. At this location, day and night are equal.
Mars is visible in the early evening western sky, beginning the month near Saturn and the 6-day old waxing crescent Moon in Libra. The planet leaves Libra mid-month, crosses Scorpius and into Ophiuchus at month end. In its travels, it passes 0.2° from the compact globular star cluster M80 on the 23rd, and 3° from Antares (Alpha Scorpii) from the 28th to 30th. M80 makes a challenging target through binoculars, being small and faint. Antares marks the heart of the Scorpion, and its ancient Greek name means rival to Mars.
Jupiter, in Cancer, can be seen rising in the east just prior to the start of morning dawn. On the 20th, the 25-day old waning crescent Moon can be seen above the rising planet.
Saturn begins the month in the early western evening sky together with Mars and the 6-day old waxing crescent Moon in Libra. Later this month, the Moon again appears close when its 4-day old slim waxing crescent is just above Saturn on the 28th.
Uranus rises after dusk in the east mid-month. The planet comes to opposition early in October and is at its best for the next two months. At 5.7 magnitude it can be seen with the unaided eye on a moonless night away from any light pollution.
Neptune, just past opposition, is high in the eastern sky in Aquarius after twilight. This distant world is easy to find in binoculars in September, spending the month within 0.7° of 4.8 magnitude Sigma Aquarii.
Comet C/2012 K1 (PANSTARRS) is at 6th magnitude in the morning sky. Beginning September in Cancer, PANSTARRS quickly moves into Hydra where it spends the rest of the month. By month’s end, the comet is rising around 3 hours before the beginning of dawn.
Through binoculars, Beta Capricorni is a bright yellow star (magnitude 3.2) with a wide white companion (magnitude 6.1) . The brighter star is actually a triple system and the white star also has a close companion so the system is actually composed of five connected stars.
A note on magnitude. This is a brightness scale of stellar objects. From one magnitude to the next, the ratio brightness is the 5th root of 100, or approximately 2.5. The lower the number the brighter the star. The brightest stars as seen from Earth are magnitude -1 (except for the Sun which is -26.7). The faintest stars visible to the unaided eye are magnitude 6 (under dark skies).
Astronomy 2014 Australia. Quasar Publishing 2013.