Every week, SkyNews publishes a list of key events in the Canadian sky in This Week’s Sky. This series gives you all the latest news in Solar System movements, including where the planets are in our sky and Moon phases. From eclipses to meteor showers, This Week’s Sky keeps you updated on the best in upcoming astronomical highlights.
Monday, August 1 – Milky Way star clusters (all night)
With the crescent Moon setting just after dusk, the extra-dark evening sky will be ideal to explore the countless knots and clumps of stars distributed along the Milky Way, many of which were included in Charles Messier’s list of the sky’s best deep-sky objects. Scan with binoculars to spot the objects, and then follow up with a backyard telescope at low magnification. Particularly good clusters include Messier 39 and the Cooling Tower Cluster (Messier 29) in Cygnus, the Wild Duck cluster (Messier 11) and Messier 26 in Scutum, the Sagittarius Star Cloud (Messier 24), and Ptolemy’s Cluster (Messier 7) and the Butterfly Cluster (Messier 6) in Scorpius.
Tuesday, August 2 – Red Mars passes blue-green Uranus (wee hours)
On the nights surrounding Tuesday, August 2, the faster orbital motion of the red planet Mars will carry it closely past the blue-green ice giant planet Uranus. At closest approach on Tuesday, 170 times brighter Mars will shine a finger’s width to the lower right (or 1.3 degrees to the celestial south) of Uranus, allowing them to share the view in a backyard telescope (inset, green circle). Note that your telescope might invert and/or mirror the scene shown here. At mid-northern latitudes the duo will clear the rooftops in the eastern sky by about 1 a.m. local time, and then remain observable for the rest of the night. Mars will increase its separation east of Uranus on the following nights, but they’ll remain binoculars-close until about August 11.
Wednesday, August 3 – Mercury races Regulus (after sunset)
Low in the west-northwestern sky for a short window after sunset on Wednesday, August 3, the speedy planet Mercury will shine telescope-close (green circle) to Leo’s brightest star Regulus. After the Sun has completely set, use your optics to seek out the five times brighter planet positioned a finger’s width to the upper right (or 1 degree to the celestial north) of the star. Most telescopes will invert and/or mirror the view shown here. Observers at tropical latitudes and farther south will see the duo shining higher and in a darker sky. On the following evening, Mercury’s orbital motion will shift it to a thumb’s width to the upper left of Regulus.
Thursday, August 4 – Lunar X and V in daytime (peaks at 21:40 UTC)
Several times a year, for a few hours just before first quarter, small features on the Moon called the Lunar X and the Lunar V become visible in strong binoculars and backyard telescopes. The bright X-shaped pattern appears when the rims of the craters Purbach, la Caille and Blanchinus are illuminated from a particular angle of sunlight. Look for it beside the terminator, about one third of the way up from the southern pole of the Moon. The Lunar V forms along the northern span of the terminator near the crater Ukert. The features will begin to develop around 4 p.m. EDT (or 1 p.m. PDT and 20:00 UTC) on Thursday, August 4, while the Moon is shining in a daylight sky in the Americas. They will peak in intensity about 90 minutes later and then disappear by about 7 p.m. EDT (or 4 p.m. PDT and 23:00 UTC). Viewing the Moon through polarized glasses in daytime will increase the image contrast. Observers in Europe and western Africa can see the phenomena while the Moon shines in a dark sky.
Friday, August 5 – First quarter Moon (at 11:07 UTC)
When the Moon completes the first quarter of its journey around Earth on Friday, August 5, at 7:07 a.m. EDT or 4:07 a.m. PDT and 11:07 UTC, its 90-degree angle away from the Sun will cause us to see the Moon half-illuminated on its eastern side. At first quarter, the Moon always rises around mid-day and sets around midnight, so it is also visible in the afternoon daytime sky, too. The evenings surrounding first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angled sunlight, especially along the terminator, the pole-to-pole boundary that separates the lit and dark hemispheres.
Saturday, August 6 – Moon in Scorpion’s claws (evening)
In the southern sky after dusk on Saturday, August 6, the waxing gibbous Moon will shine in western Scorpius, between that constellation’s brightest star, reddish Antares, and the up-down row of small white stars that form the scorpion’s claws, Jabbah or Nu Scorpii, Graffias or Acrab, Dschubba, Pi Scorpii and Rho Scorpii. A backyard telescope at high magnification will reveal that Nu Scorpii, Graffias and Dschubba are close-together double stars.
Sunday, August 7 – Mare Imbrium’s Golden Handle (all night)
On Sunday night, August 7, the terminator on the waxing gibbous Moon will fall just west of Sinus Iridum, the Bay of Rainbows. That semi-circular feature, 249 kilometres in diameter, is a large impact crater that has been flooded by the same basalts that filled the much larger Mare Imbrium to its east, forming a rounded “handle” on the western edge of the mare. The “Golden Handle” effect is produced when low-angled sunlight brightens the prominent Montes Jura mountain range surrounding Sinus Iridum on the north and west. Sinus Iridum is almost craterless, but hosts a set of northeast-oriented wrinkle ridges that are revealed at this phase.
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the Universe together.