This month opens with the moon in its waning gibbous state, meaning it is reducing in illuminated size and the lit portion has a "humped" or "bulging outward" shape. The moon is also at apogee, 405,036 kilometres. Compare this to the perigee distance July 13 of 361,115 kilometres - nearly 44,000 kilometres difference and a reminder that planetary orbits are not circular, but elliptical.
July 3, Jupiter is seven degrees south of our satellite; July 8, it is within a degree of the Pleiades (Seven Sisters); July 9, it glides through the cluster M35; July 11 is new moon and a total solar eclipse in the South Pacific, just off Tahiti for some observers on board ship there. July 15 and 16, Venus, Mars and Saturn are within close proximity of the moon; by July 21, Antares is a little less than two degrees south; and the moon is full July 25.
Mercury will be visible for the last three weeks of July in the western sky shortly after sunset. July 12, the swift planet is close to the young sliver of a day-old moon; later in the day, Mercury is less than a half degree from the Beehive Cluster, M44. July 27, Mercury is within a half degree of Regulus.
Venus continues to brighten the western evening sky all month. As mentioned above, it will be within a few degrees of the nearly first-quarter moon July 15. As an aside, "first quarter" does not refer to the moon's lit portion, but to the fraction of the month - seven days from new to first quarter; 14 days to full; 21 days to third quarter; 28 days to new (approximately).
Mars is visible as a faint orange speck in the western evening sky, moving from Leo into Virgo. A telescope only shows that it is a disk, but not much else. The Red Planet is 167.4 million kilometres away at the beginning of July.
Jupiter rises in the east just after midnight, and is due south at 5:30 a.m. in the early part of the month. The giant planet begins retrograde motion (westward among the stars) July 24.
Saturn is in the western evening sky, along with Mars and Venus, as the month opens. Watch for the moon with this trio July 15 and 16, as noted above. The Ringed Planet is quickly closing in on Mars and Venus by month end.
Uranus and Neptune are early morning risers; they are within a hand width of each other, and skirt along the horizon until daybreak. The moon glides by Uranus on the morning of July 3.
- James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000. He is editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal, and is the society's national secretary.
