Deep Southern Skies - August 2015
Village Journal 310
Welcome to a monthly description of our northern NSW night sky.
Mercury at best for evening viewing.
Mars and Regulus close.
Jupiter, Mars and Venus make for a pre- dawn alignment.
5th Last Quarter. 13th New Moon.
14th Moon at apogee (farthest from Earth at 406,464 km)*.
21st First Quarter.
28th Moon at perigee (closest to Earth at 356,877 km)*.
28th Full Moon.
Take a look at the two images of the Moon to see the difference in appearance at these two distances from Earth that occur each Lunar month (29 days).
Mercury is at its best for observation in the western evening sky for the first three weeks of the month. Locating the planet is straight- forward as it meanders in Virgo below the 1st magnitude star Spica (Alpha Virginis), and can be seen in the dark sky after the end of twilight. On the 15th, the slender crescent of the 2-day old Moon appears to the north (right) of the planet.
Venus begins as the Morning Star, staying this way till June 2016. Bright and bold in the morning dawn, the planet spends most of the month in Cancer before moving into Leo. On the 10th, the 26-day old waning crescent Moon appears to the north (left) of Venus.The planet also reaches its greatest illu- minated extent on the 22nd at a very bright -4.5 magnitude.
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 with
day and night equal.
Mars is visible in the eastern dawn sky, moving through Cancer during the first week of the month before crossing into Leo. On the 11th, the 27-day old waning crescent Moon appears above and south (right) of the planet. From the 24th to 26th, Mars passes within 1° of Regulus (Alpha Leonis), the brightest star in Leo.
Jupiter returns to the eastern dawn sky in Leo. By month end, Jupiter, Mars and Venus will be seen together in the constellation of the Lion. Try to catch this great alignment if you are up early!
Saturn is visible in the early western evening sky after dusk, setting prior to midnight.
On the 19th, the 5-day old waxing crescent Moon appears nearby the planet. On the 20th, Comet Tempel 2 is only 2.3° north of Saturn.
Uranus rises after dusk in the east and is visible for the rest of the night as it heads towards opposition next month. At 5.7 magnitude Uranus is visible to the unaided eye under dark skies.
Neptune is at oppo- sition on the 1st and is visible in the east- ern sky after twilight in Aquarius. Tele- scopes larger than 100 mm diameter
with moderate magnification will resolve the planet into a small bluish disk.
Dwarf Planets and Small Solar System Bodies
Pluto, in Sagittarius, is an evening object crossing the meridian (due north) around 7 pm mid-month. It appears stationary on the 24th as it ends six months of retrograde motion, thereafter it returns to a west to east direction against the star field.
Comet 10P/Tempel 2 starts the month at 11th magnitude in Libra where it remains until late September when it moves into Scor- pius. Setting late in the evening, the first half of the month will see no moonlight interfer- ence and Tempel 2 remains approximately 9° from comet Kopff during the month.
Comet 22P/Kopff remains at 12th magni- tude and in Libra throughout September, setting mid-evening. Best observing will be the first half of the month when the sky is Moonless.
Comet C/2013 US10 (Catalina) opens in September in the constellation of Norma when it might be 7th magnitude in bright- ness. Quickly moving into Circus and Lupus, Catalina is best observed in the evening sky before it ends the month in Centaurus.
Astronomy 2015 Australia. Quasar Publish- ing 2014.
The SkyX Professional Edition planetarium software.
Lunar image, Chander Devgun credit.