The Sky This Month – June 2010
Overview
This month brings good news and bad news for stargazers.
The good news: All seven major planets are visible this month, as well as a bright “dwarf planet” that grazes the lovely Lagoon Nebula in Sagittarius. Even better… the star-sparse skies of spring give way to the brighter summer stars and the deep-sky delights of the Milky Way that arcs overhead after midnight.
The bad news: the long days of June mean the stars aren’t visible until after 10-11 p.m. local time in northern latitudes. And at 50ºN or higher, the sky never truly gets dark, since the sun dips only 16.5º or less below the horizon on June 21. Above the Arctic Circle, the sun never sets at this time of year.
Of course, this is all reversed for observers in the southern hemisphere. The cool first days of a southern winter mean long, dark nights and excellent views towards the center of the Milky Way and the thick star clouds of the constellations Sagittarius and Scorpius.
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Speaking of Scorpius, the great celestial scorpion makes a grand entrance, rising head-first over the southeast horizon about 11 p.m. local time by mid-month in mid-northern latitudes, and before sunset in the south. The three bright stars that mark the head of Scorpius are, from north to south: Graffias (also called Achrab), Dschubba, and π Scorpii.
Graffias is a fascinating star. A small telescope easily shows it as a pretty double star. But closer inspection by professional astronomers indirectly reveals Graffias to be at least a quintuple-star system… almost like a mini star cluster. The brightest of this group is some 20,000 times brighter than our sun. Like Graffias, Dschubba and π Scorpii are also multiple-star systems of mostly hot blue stars. These stars all lie about 400-600 light years from Earth. Like most of the bright stars in this part of the sky, they will one day explode as supernovae and appear bright enough in our night sky to cast shadows for a few weeks or month. Though not for a few million years or so.
If you have binoculars or a small telescope, try to spot the globular clusters M80 and NGC 6144 nestled among the lead stars of Scorpius. And look for the somewhat sparser globular cluster M4 just 1.3 degrees west of the red-orange Antares, the brightest star in Scorpius.
The constellation Scorpius as it will appear at mid-northern latitudes on and around June 15 (click to enlarge).
Moon
Last Quarter: June 4, 22:14 UT (GMT)
New Moon: June 12, 11:15 UT
First Quarter: June 19, 04:29 UT
Full Moon: June 26, 11:30 UT (partial eclipse visible in Australia, New Zealand, western North America, and most of the Pacific)
Planets
Mercury. After a magnificent sunset apparition in April, this baked little world swung back around the sun in May and comes back into view just before dawn this month. Look for it about a fist-width below the thin crescent Moon before sunrise on June 10.
Venus dominates the sky at sunset, shining at magnitude -4.0. You can’t miss it. The dazzling planet is just above the crescent Moon on June 14, and lies within a degree of the Beehive star cluster on June 19. The pair will make a fine sight in a small telescope.
Mars. The Red Planet isn’t much to look at in a telescope, but it intrudes upon the sickle-shape of the constellation Leo when it comes to within a degree of the bright star Regulus on June 6. This is a great time to compare the orange-red color of Mars against the icy white of Regulus.
Jupiter and Uranus linger in Pisces and rise earlier each night. The two planets lie within one degree of each other for most of the month, so if you can find Jupiter, you get Uranus for no extra charge. Look for Jupiter low in the southeast a couple hours after midnight: it’s the brightest star-like object in this part of the sky. Though it’s best observed just before dawn when it’s higher in the sky.
On June 8, Uranus and Jupiter make their closest approach when the planets are less than 1/2 degree apart. Uranus will be just to the northwest of Jupiter. At magnitude 5.9, Uranus is easily seen in binoculars along with Jupiter and its moons. Through a telescope, you may see a slight blue-green color in the tiny disk of this distant world. Though you will need at least 75-100x to discern the disk at all.
Saturn lingers in Virgo, not far from the field of galaxies between Denebola and Vindemiatrix. The planet dims over the month. You can still see the rings as they appear to be sticking out of the planet like tiny “spikes”. The rings will slowly tilt more towards Earth over the coming years, causing the planet to brighten and present a more pleasing view in a telescope.
Neptune. The ninth-magnitude planet sits on the border between Capricorn and Aquarius. Like Jupiter and Uranus, it rises near midnight at moves towards its highest point in the sky by dawn.
Celestial Events
June 1-2. The dwarf planet Ceres passes through the southern part of the lovely Lagoon Nebula (M8) in Sagittarius (see image at top of page). Ceres was once classified as an asteroid, but the big brass of the astronomy world reclassified it as a “dwarf planet” along with Pluto and many others. Ceres shines at a respectable magnitude 7.5 as it passes M8… bright enough to see in binoculars. A small telescope gives you an even better view. In February 2015, NASA’s Dawn space probe takes up orbit around Ceres to learn more about this near-planet.
A Stellarium illustration of the dwarf planet Ceres grazing the southern edge of the Lagoon Nebula, M8, just after midnight on June 2, 2010 (click to enlarge).
The Lagoon Nebula itself is just above and to the right of the top of the “teapot” of Sagitarrius, which is the constellation east of Scorpius. Here’s an image of the area to help you find it in the southern sky.
June 6. Jupiter and Uranus are within a degree of each other and sit just below the waning Moon before dawn. And remember to look for the extra “star” in the constellation Leo tonight… it’s the planet Mars, less than a degree from Regulus.
June 21. Summer begins in the northern hemisphere at 11:28 GMT when the sun reaches its highest point on the ecliptic. At latitude 23.5º N, where the Tropic of Cancer begins, the sun will be directly overhead around noon and will cast no shadow. By definition, winter begins in the southern hemisphere at the same time summer begins in the north.
June 26. A partial lunar eclipse will be visible in western North America at dawn, and through the Pacific in the evening. Best places to see this are New Zealand, Australia (except the far west), and most Pacific islands.
