June 2008

Skywatchers’ Guide for June 2008

PLANETS

Saturn and Mars both lose altitude in June 2008. This chart shows the western evening sky at around 9:15 p.m. MST during early June and 8:15 p.m. MST during middle June. The Moon is shown for June 7-8. This sky chart shows Saturn, Mars, Regulus and the western evening sky on June 23 and June 30 at around 8:30 p.m. MST from the Desert Southwest. This sky chart is most useful for the continental United States, Hawaii, southern Canada and northern Mexico. This sky chart shows Jupiter, the Moon and the southeastern evening sky on June 18-19 at around 9:30 p.m. MST from southern Arizona. This sky chart shows Mercury, the Moon and the eastern morning sky on June 30 at around 4:30 a.m. MST from southern Arizona. This sky chart is most useful for the continental United States, Hawaii, southern Canada and northern Mexico.

Mars creeps closer in our sky to Saturn and the bright star Regulus in the evening sky this month, with the Moon making for rare and interesting groupings on June 7 and 8. This is a preview of the spectacular grouping of these same four objects later on July 5 and 6. By June 30 Mars is only 0.43 degrees from Regulus in our sky (see below).

Mars is visible starting 30 minutes after sunset this month and starts the month conveniently high in the western sky in evening twilight. However the Red Planet continues to shrink in apparent size (from 4.9 to a tiny 4.5 arc seconds) and fade (from magnitude 1.5 to 1.7) by the end of June as Earth continues to recede from Mars in space. Mars drifts 0.5 degrees per day in June towards Saturn, moving through Cancer the Crab and into Leo, the Lion. Look for the 5 day old waxing crescent Moon only 1.2 degrees below Mars in our sky on Saturday evening June 7. Mars will be within one degree and closest to Saturn in our sky by July 10 and 11. The Mars Phoenix Mission, led by the University of Arizona, has successfully landed on the north pole of Mars! For information on and images from this first University led mission to another planet see the Phoenix Mars Mission Home page

June 2008 should provide the year’s last chance for sharp views of Saturn and its ring system as Saturn is sinking in the western evening sky. Saturn continues to gradually fade and becomes a 0.9 magnitude star-like object in June. The ringed planet is dimmer this year (compared to previous years) because its rings are more edge-on, and will be seen increasingly edge-on as the year progresses. Early in June Saturn is found high in the western sky in the constellation of Leo the Lion during the convenient evening hours (well placed for telescopic viewing at about 50 degrees in altitude at 8 p.m.) but moves lower by the end of the month. Saturn continues eastward or ‘direct’ motion, drifting farther (from three to over four degrees) from Leo’s brightest star Regulus this month. With Saturn directly 90 degrees east of the Sun in our sky on June 22, late May and early June are excellent times to see the shadow Saturn casts on its rings. 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. Saturn sets in the west at around 12:40 a.m. by June 1 but at midnight on June 10. Also, the 6 day old waxing crescent Moon is near Regulus and Saturn and (only 1.4 degrees below Regulus) in our sky on Sunday evening June 8, a preview of the spectacular grouping of the Moon, Saturn, Regulus and Mars later on July 5 and 6.

Bright Jupiter is rising by 10:30 p.m. in early June but just after 8:00 p.m at the end of June. The bright giant world is highest (at over 30 degrees from the southern United States) in the southern sky in early June the start of morning twilight. By June 30 Jupiter is highest (transiting the southern horizon) by 1:10 a.m. Whitish Jupiter is east of the Teapot of Sagittarius and is the brightest star-like object that is well up in the late night sky. The waning gibbous Moon slides well below Jupiter in our sky on Thursday evening June 19.

The Brilliant planet Venus has sunk out of sight into the glare of the Sun and will not be easily visible to the unaided eye until August.

Mercury fades into view after June 25 in the morning sky. Mercury is visible above a clear east-northeastern horizon in late June, starting 50 minutes before sunrise. Mercury is brightest and creeps higher at the very end of June in the morning sky. Observers in most of the continental United States (including mid-northern latitudes) can see Mercury at around 5 degrees above the eastern horizon on June 30 (at around magnitude +0.6, but dimmed by its low position in the sky). Mercury is higher and brighter in July. Also look for the thin waxing crescent Moon 15 degrees above Mercury in our sky on the morning of June 30. The first spacecraft to orbit Mercury, the MESSENGER spacecraft, arrived early this year in its first flyby of Mercury. For a link to see the latest images, and find details about the MESSENGER spacecraft and the Mission Operations Center, click here.

Visitors to Flandrau’s 16-inch telescope should note that Mars and Saturn are both visible in the telescope during public hours. Flandrau’s 16-inch telescope is open for viewing during public hours, weather permitting, Wednesday through Saturday nights (excluding select holidays), from 7-10 p.m. 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 Mercury or even Mars this month, note that they do appear to twinkle somewhat; 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. 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. 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. This chart shows the Milky Way and the southern sky from the Desert Southwest at 11:00 p.m. in early June, 10 p.m. in mid-June and 9 p.m. in late June.

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!
Look for the Milky Way to rise late and become visible from dark locations on moon-less June evenings; It will be brightest around the constellation Scorpius, the Scorpion. The Milky Way, the galaxy of stars, gas and dust our solar system resides in, is prominent all summer long, but is brightest after midnight in 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 stretching 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.

Summer Solstice on Friday, 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 for southern Arizona on the afternoon of Friday, June 20, at 4:59 p.m. (MST or Tucson time). 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 new moon in June occurs on Tuesday June 3, also the date of the second closest perigee Moon of the year; High tides are expected in coastal areas. The June first quarter Moon will occur on Tuesday evening, June 10. The June Full Rose Moon (as named by Europeans) rises on the evening of Wednesday, June 18 and sets on the morning of Thursday, June 19. The June 2008 last quarter Moon will occur on Thursday morning June 26.

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