This Week’s Sky at a Glance, June 30 – July 7 ~by Curt Nason
Arrows are used in signs as pointers to direct us to notable sites. As the Summer Triangle of the bright stars Vega, Deneb and Altair rise high in late evening, the tiny constellation of Sagitta the Arrow can direct us to a few interesting binocular objects. Sagitta is a compact arrow situated halfway between Altair and Albireo, which form the heads of Aquila the Eagle and Cygnus the Swan. Albireo itself is an interesting binocular object, being revealed as two colourful stars.
Looking under the shaft of the arrow with binoculars you might notice a hazy patch of stars called M71, which is a globular cluster containing more than 10,000 stars. As globular clusters go it is younger than most and relatively small. Half a binocular field above the arrowhead is ghostly M27, the Dumbbell Nebula. This is a planetary nebula; gases emitted from a Sun-sized star as its nuclear fuel was running out. The star collapsed into a hot, dense Earth-sized star called a white dwarf, and the ultraviolet radiation emitted from it causes the gases to glow. In older photographs of M27 its bipolar shape resembled a dumbbell. About a binocular width to the upper right of the arrow’s feathers is an asterism called the Coathanger cluster, a favourite treat for closet astronomers.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 5:31 am and sunset will occur at 9:14 pm, giving 15 hours, 43 minutes of daylight (5:39 am and 9:15 pm in Saint John). Next Saturday the Sun will rise at 5:35 am and set at 9:11 pm, giving 15 hours, 36 minutes of daylight (5:44 am and 9:13 pm in Saint John). Next Friday afternoon the earth is at aphelion, its farthest distance from the Sun for the year. Keep a sweater handy.
The Moon is near Mars this Saturday and it is at third quarter next Friday. Mercury is moving toward Venus, setting an hour and a half after sunset midweek, but it is also dimming. Bright Venus sets 45 minutes after Mercury. Jupiter and its moons put on a different show every evening, and its Red Spot can be seen with a telescope around 11 pm on Monday and 10 pm next Saturday. Saturn is now in our sky at sunset, flaunting its rings of ice particles in small telescopes. There are reports that the dust storm on Mars is starting to thin, making astronomers more hopeful that it will yield views of its polar ice cap and basaltic ground this summer.
The Saint John Astronomy Club meets in the Rockwood Park Interpretation Centre on Saturday, July 7 at 7 pm. All are welcome.
Questions? Contact Curt Nason.