Skywatchers’ Guide for June 2010

Mars and Regulus group closely in our western evening sky on June 5 at 8:45 p.m. Venus (below the two) is also shown. Venus and the Moon appear fairly close in our sky on June 14 at 8:45 p.m. Mars (above) is also shown. Mars, Regulus and the Moon are shown on June 16 at 8:45 p.m. along with the Saturn, Venus and the current western evening twilight sky.

HIGHLIGHTS: June 2010 features the close groupings or ‘conjunctions’ of planets (Jupiter with Uranus, and Mars with a bright star; these are best visible in telescopes at low power). Saturn, now in the western evening sky, is still conveniently high up in the sky for evening telescopic viewing, and is highest overhead in twilight. The rings of Saturn appear very thin, as we view them nearly edge-on from Earth. Brilliant Venus is our ‘evening star’ in the west and highest this month while Jupiter, our ‘morning star’ is moving high in the eastern morning twilight sky. Jupiter groups closely with Uranus this month, the first of three such ‘conjunctions’ .

PLANETS

June 2010 continues to be a very good time to see Saturn and its ring system as Saturn doesn’t set until well after midnight. Saturn fades slightly to around magnitude 1.1 this month. Although the ringed planet is somewhat dimmer this year (compared to previous years) because its rings are more edge-on, it’s easy to see during the evening hours and is well placed for telescopic viewing. Look for Saturn conveniently overhead in evening twilight in the constellation Virgo the Virgin (though well east of Spica, Virgo’s brightest star).

Saturn’s rings still appear nearly as ‘narrow’ as they did earlier this year, due to our vantage point on Earth. The ringed world stopped its retrograde motion on May 31, when it was stationary and resumes eastward or ‘direct’ motion in June. The 7-day old first quarter Moon passes about 8 degrees below (south) of Saturn on the evening of June 18.

Best views of any planet should be when it is highest in the sky, but viewing is dependent on atmospheric stability and conditions, and of course, the quality and size of the telescope used. Large, high quality amateur telescopes in good “seeing” (stable atmospheric conditions) will best reveal any features on a planet’s disk.

The brilliant planet Venus continues to gain altitude early in the month, rising to the highest it will attain in our evening twilight sky this year. Venus is moving rapidly against the background stars. Early in June it passes out of Gemini, the Twins, moving through Cancer, the Crab mid-month and into the western boundary of Leo, the Lion by the end of the month. By June 20 Venus is only 2/3 of a degree from “The Beehive”, a bright star cluster in Cancer, the Crab. (To view this use binoculars or a wide-field telescope at low power.) In a fairly dark sky, Venus is visible approaching the cluster the week before. “The Beehive” appears as a patch of fuzzy light to the naked eye in a dark sky but Venus overwhelms the cluster with its brightness in the evenings around June 20. Also look for the razor thin, 2 day old waxing crescent Moon to pass some 4 degrees from Venus on the evening of Monday, June 14. The 3 day old Moon will lie well east (left of) Venus on June 15.

Mars continues to fade this month and is in the western half of the sky after the end of evening twilight. It groups very closely with the bright blue-white star Regulus in the constellation Leo, the Lion early in the month. The two objects appear less than 2 degrees apart on June 3-9, and are only ½ degree apart on June 6-7 (a spectacular view in a telescope). Orange-reddish Mars fades in June to first magnitude in brightness, and is shrinks to below 6 arc seconds in diameter. Mars is a long way off from Earth (hence its faintness compared to Venus) and so is currently an unremarkable object in a telescope. Mars, like Venus, is moving rapidly against the background stars as Earth continues to recede from it in our solar system. On the evening of June 16 look for the 5-day old waxing crescent Moon to pass about 5 degrees ‘below’ (southwest of) Regulus. The following evening the 6 day old Moon lies about 9 degrees ‘left’ (southeast of) Mars on June 17.

Bright Jupiter continues to gain altitude and rise earlier each morning in the east-southeastern sky, and is now high enough for quality telescopic viewing, starting one hour before sunrise (especially during the last half of June). Jupiter groups closely with Uranus this month and this is the first of three such ‘conjunctions’ (with the other two on September 22 and January 2, 2011). Bluish Uranus is best visible in a low power telescope nearest Jupiter from June 1-16, with the very best view of the two only ½ degree apart on June 6-10. By June 30 Jupiter is some 46 degrees above the east-southeastern horizon, around 90 minutes before sunrise. The thin 24-day old waning crescent Moon passes about 6 degrees above (northeast) of the giant gas planet on the morning of June 6.

Mercury is lost in the glare of the Sun this month for casual observers. It is much better seen from the Southern Hemisphere. It was at greatest elongation from the Sun on May 26, when it appeared at 0.6 magnitude, some 4 degrees above the eastern horizon, 45 minutes before sunrise. The first few days of June it might be visible in binoculars in a very clear sky, but dimmer and lower above the eastern dawn horizon.

Visitors to Flandrau’s 16-inch telescope should note of the planets Saturn is visible in the telescope during public hours, and other celestial objects will be shown in the telescope, weather permitting. Flandrau’s telescope remains open for viewing during public hours from 7-10 p.m., weather permitting, Wednesday through Saturday nights (excluding select holidays).

Finally, remember that in spotting planets there is a general rule: ’stars twinkle, planets don’t’. This is because stars are point sources of light; therefore starlight is easily disturbed and shifted by air currents in the Earth’s atmosphere. However when looking at Mars this month, note that it may appear to twinkle somewhat when near the horizon; however, this twinkling is of a slower nature than that of the bright stars.

JUNE EVENING STARS

The "pointer stars" of the Big Dipper, Dubhe and Merak, point down to the North Star, ‘Polaris’. This sky chart shows the Desert Southwest sky in early June at 10:30 p.m. and in mid June at 9:30 p.m. "Arc to Arcturus": This sky chart shows the western sky at 10:30 p.m. in early June, at 9:30 p.m. in mid-June and at 8:30 p.m. in late June. No planets are shown. The bright stars Antares and Vega provide a color contrast in the bright summer Milky Way. This sky chart shows the sky in early June at 11PM, in middle June at 10PM and late June at 9PM, and is most useful for the southern United States and northern Mexico.

The Big Dipper is easy to find in June, high in the northern evening sky. Look for the Big Dipper high in the north 1 hour after sunset. Take the two end stars off of the bowl (the Pointer stars) and point down to Polaris, the North Star. Polaris is a star of ordinary brightness, and marks the end of the handle of the Little Dipper. Polaris can also be found about 30 degrees (or 3 fists) above the northern horizon. Polaris stays put in the sky; to the eye it doesn’t appear to move. This is because Earth’s axis is pointed toward Polaris in space.

Bright stars of the June evening sky (1 hour after sunset) include ruddy Antares in the southeast, the bright yellow star Arcturus high overhead, and the blue star Spica, high in the south. Locate the bright yellow star Arcturus and the blue star Spica by recalling, “Follow the arc (of Big Dipper’s handle) to Arcturus and drive a spike to Spica”, or simply “Arc to Arcturus and spike to Spica”. Although Spica is said to mark the spike or ear of wheat in the hand of Virgo, it really looks like the bottom of a group of stars in Virgo that make up a diamond or kite shape.

Rising above the northeastern horizon in early June one hour after sunset is bright Vega, the brightest star of the summer sky. Blue-white Vega in the northeast contrasts sharply with Antares, the baleful red supergiant star of summer, now rising in the southeast in early June evenings. By late June its orange-red twinkling enlivens the southern sky, giving reason to its name “the rival of Mars”. From the southern United States Antares does not get very high, only about 30 degrees (or three fists held at arm’s length) above the southern horizon, because of its position in the southern sky. However, from Australia Antares can be seen overhead in June and July. Antares is the brightest part of a most impressive scroll of stars, sort of like a long letter “S” fallen halfway forward. In this case the “S” stands for the constellation it is part of: Scorpius.

The Milky Way Prominent in the Late Night Hours!

The Milky Way, the galaxy of stars, gas and dust our solar system resides in, is prominent all summer long, and rises in the early June sky after 11 p.m., but earlier, by 9 p.m. in late June. To see it, you’ll need to get away from city lights to a dark location, and look on a night when there’s not much interference from the moon. The Milky Way will appear as a “cloudy” band clear across the sky. High power binoculars and telescopes reveal the Milky Way to be clouds of stars, millions of them, with attendant star clusters and gas clouds making up some of the “fuzzier” spots you’ll see.

THE SUMMER SOLSTICE IS ON JUNE 20

The Sun continues to move higher in our early June sky, hence the warmer temperatures. On the date of the summer solstice the Sun will be highest this year in the northern hemisphere sky at local noon and will set furthest in the northwest. This year the northern hemisphere summer solstice occurs on Sunday, June 20 at 6 p.m. MST for western North America. Summer begins then as the Sun stands directly at local noon over the Tropic of Cancer. Throughout the northern hemisphere, the solstice midday Sun is the highest of the year, and days are longest.

MOON PHASES

The June last quarter Moon occurs on Friday evening, June 4. The June new moon occurs on Saturday, June 12. The June 2010 first quarter Moon will occur on Saturday, June 19. The June Full “Rose” Moon will rise on the evening of Saturday, June 26 and set on the morning of Sunday, June 27. There will be a partial lunar eclipse that evening, the first 0ne visible since February 2008.

These dates and times are for southern Arizona, and are not necessarily Greenwich Mean Time dates, the moon phase dates used for calendars.

Note: Additional information can be accessed by phone at Flandrau Science Center’s Astronomy Newsline at (520) 621-4310 or as a menu option at 621-S-T-A-R.

Graphics done using Starry Night Pro, Starry Night Enthusiast and Adobe Photoshop. To purchase Starry Night Pro or Enthusiast, go to http://StarryNight.com