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July 2007

Skywatcher’s Guide for July 2007

PLANETS

This sky chart shows the planets Saturn and Venus in the western sky on July 1, one hour after sunset at around 8:35 p.m. from southern Arizona. This sky chart is most useful for the continental United States, southermost Canada and northern Mexico.
This sky chart shows the planets Saturn and Venus in the western sky on July 1, one hour after sunset at around 8:35 p.m. from southern Arizona. This sky chart is most useful for the continental United States, southermost Canada and northern Mexico.
This sky chart shows Jupiter and the southern evening sky in middle to late July, one hour after sunset at around 8:35 p.m. from southern Arizona. The Moon is shown for July 24. This sky chart is most useful for the continental United States, southermost Canada and northern Mexico.
This sky chart shows Jupiter and the southern evening sky in middle to late July, one hour after sunset at around 8:35 p.m. from southern Arizona. The Moon is shown for July 24. This sky chart is most useful for the continental United States, southermost Canada and northern Mexico.
This sky chart shows Mars and the eastern pre-dawn sky on July 9 at around 1:30 a.m. but is useful for several days around July 9. This sky chart is most useful for those viewing from the continental United States, southermost Canada and northern Mexico.
This sky chart shows Mars and the eastern pre-dawn sky on July 9 at around 1:30 a.m. but is useful for several days around July 9. This sky chart is most useful for those viewing from the continental United States, southermost Canada and northern Mexico.

Saturn and Venus group in the west; Jupiter bright and large in a telescope

July 2007 finds Saturn slowly sinking out of view in the western evening sky. But, like last month, what makes this month’s views of Saturn particularly interesting is its close proximity to the planet Venus at the start of July. On Sunday, July 1st Saturn and Venus will be grouped within one-half of one degree of sky offering skywatchers a great opportunity to use a telescope to view both planets in a single field of view. This is the best overall grouping of two bright planets this year. Afterwards, Venus and Saturn slowly drift farther apart in our sky, but for much of July, Venus and Saturn are loosely grouped with the bright star Regulus, in Leo, the Lion. By Monday, July 16 the waxing crescent Moon enters the scene adding to an already beautiful grouping of Venus, Saturn, and Regulus.

Saturn is only high enough in the sky early in July for brief viewing of its amazing rings in Flandrau’s 16-inch observatory telescope, weather permitting. Viewing of Saturn’s rings may be briefly available for about 20 minutes during the first week of July (weather permitting) by 7:45 p.m. Because Saturn is slowly sinking out of view, visitors should come early in the month to view it (Saturn will be too low to view by 8:15 p.m., mid-month). Saturn appears to the unaided eye as a zero magnitude star-like object that does not twinkle. As with any planet, viewing is dependent on atmospheric stability and conditions, and of course, the quality and size of the telescope used.

Brilliant Venus, grouped wonderfully close to Saturn early in the month (see above), is slowly sinking out of view along with Saturn. This month and next is a wonderful time to look at Venus in a telescope as its phase becomes an ever thinner crescent. Venus sets earlier and is closer to the horizon each evening. By the end of July it’s setting a little more than one hour after the Sun. The 3 day-old waxing crescent Moon will be near Venus (but closer to Saturn) in our evening twilight sky on Monday, July 16, while above Venus on Tuesday, July 17 again adding to a beautiful grouping of Venus, Saturn, and Regulus..

Bright Jupiter was closest to Earth and farthest from the Sun (at opposition) on June 5 and is still bright and large in a telescope in July. In fact, weather permitting, July is the best month to view it in the convenient evening hours just after sunset. Jupiter is located in the east or front portions of Scorpius, the Scorpion and easily found 90 minutes to 1 hour after sunset in the southeast. Jupiter is highest (at 35 degrees in altitude) due south at 11 p.m. in early July, at 10 p.m. in mid-July, and at 9 p.m. in late-July. The giant planet is located in our sky not far from the reddish super-giant star Antares for much of the month. Jupiter is about 5 degrees away from Antares (the Rival of Mars, and the heart of the Scorpion) all month long. Also, look for the waxing gibbous Moon to be near and west of Jupiter this month in the southern sky on Tuesday evening, July 24. The Moon to be near but east of Jupiter in the southern sky on Wednesday evening, July 25.

Mars is slowly brightening and is now 0.5 magnitude: It’s now over 35 degrees in altitude above the east-southeastern horizon, 90 minutes before sunrise, mid-month. Mars drifts eastward out of the constellation Pisces, the Fish and into southern portions of Aries, the Ram this month. The thick waning crescent Moon will rise near Mars around 1 a.m. on Monday, July 9 and both can be seen near each other that morning.

Mercury is visible a few (about 5) degrees above the eastern horizon in the morning twilight at 4:30 a.m. from July 18-28. Mercury will be at greatest elongation from the Sun on July 20th and will be 0.3 magnitude in brightness.

Visitors to Flandrau’s 16-inch telescope should note that the planets Venus and Saturn are briefly visible in the telescope during early July, with Jupiter in view late all month long. Viewing of Saturn and Venus may be briefly available for about 20 minutes during the first week of July (weather permitting) by 7:45 p.m. The telescope is normally open from 7 – 10 p.m. Wednesday through Saturday, weather permitting. The telescope will be closed on July 4th for the Independence Day holiday.

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 right now, it may appear to twinkle somewhat; however, this twinkling is of a slower nature than the bright stars.

JULY EVENING STARS

The northern evening sky in early July at 10:30 p.m., in middle at 9:30 p.m. and in late July at 8:30 p.m. The “pointer stars” of the Big Dipper, Dubhe and Merak, point down to the ‘North Star’, Polaris. This sky chart is useful throughout the USA.
The northern evening sky in early July at 10:30 p.m., in middle at 9:30 p.m. and in late July at 8:30 p.m. The “pointer stars” of the Big Dipper, Dubhe and Merak, point down to the ‘North Star’, Polaris. This sky chart is useful throughout the USA.

This sky chart shows much of the western half of the sky at 10:30 p.m. in early July, at 9:30 p.m. in middle July and at 8:30 p.m. in late July. This star chart is useful for the entire United States.
This sky chart shows much of the western half of the sky at 10:30 p.m. in early July, at 9:30 p.m. in middle July and at 8:30 p.m. in late July. This star chart is useful for the entire United States.
This sky chart shows much of the southeastern section of the sky at 10:40 PM in early July, at 9:40 PM in mid-July and at 8:40 PM in late July. Jupiter is not shown on this sky chart for 2007. This chart is useful for the entire United States, but is most accurate for the southern U.S.
This sky chart shows much of the southeastern section of the sky at 10:40 PM in early July, at 9:40 PM in mid-July and at 8:40 PM in late July. Jupiter is not shown on this sky chart for 2007. This chart is useful for the entire United States, but is most accurate for the southern U.S.

The Big Dipper is easy to find in July, high in the northern half of the 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 July evening sky (1 hour after sunset) include ruddy Antares in the south, the bright yellow star Arcturus high overhead, and the blue star Spica, high in the southwest. 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.

High above the northeastern horizon in early July one hour after sunset is bright Vega, the brightest star of the summer sky. Blue-white Vega high in the northeastern sky contrasts sharply with Antares, the baleful red super-giant star of summer, now above the southern horizon in early July evenings. Throughout July the orange-red twinkling of Antares 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 (due to its location in the southern sky). From Australia though 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. And in this case the S stands for the constellation it is part of: Scorpius. From Australia though 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. And in this case the S stands for the constellation it is part of: Scorpius.

The Milky Way Prominent in the Late Night Hours!

The sky as seen looking toward the south in early July at 3:15 AM. This star chart is most useful for the southern half of the United States and northern Mexico.
The sky as seen looking toward the south in early July at 3:15 AM. This star chart is most useful for the southern half of the United States and northern Mexico.

This sky chart shows the Milky Way rising high above the eastern sky at 9:30 p.m in early July and at 8:30 p.m. in late July.. This sky chart is useful throughout much of the USA.
This sky chart shows the Milky Way rising high above the eastern sky at 9:30 p.m in early July and at 8:30 p.m. in late July.. This sky chart is useful throughout much of the USA.

Look for the Milky Way to rise late on moon-less July evenings; It will be brightest around the constellation Scorpius, the Scorpion in the south. The Milky Way, the galaxy of stars, gas and dust our solar system resides in, is prominent all summer long, and is brightest after 10 p.m. in early July, but by late July can be seen well at the end of evening twilight. 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.

MOON PHASES

The last quarter Moon will occur on Saturday morning, July 7th. The July new moon will be on Saturday July 14. The July first quarter Moon will be on the evening of Saturday July 21. That evening the bright star Spica, in Virgo, will be upper right of the moon. The July full moon is the Full ‘Buck’ or ‘Thunder’, which will occur on Sunday night July 29th into the morning of Monday July 30th. This full moon is the second lowest in the sky this year, and should appear deceptively large to many people.

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 Enthusiast and Adobe Photoshop. To purchase Starry Night Enthusiast go to http://StarryNight.com

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