Star calendar for July–September 2010

By Arnold Medalen

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Star Calendar

• July


• August


• September

New moon

Full moon

July

1 Jul
Saturn, Mars, Regulus and Venus form a line from upper left to lower right just above the western horizon at sunset. To the upper right, the Big Dipper sits with its handle above the bowl. The moon is at apogee, 63.51 Earth-radii away.

3 Jul
Look high in the southeast just before sunrise to find Jupiter 3 finger-widths to the moon’s lower left.

4 Jul
For the next week or so, watch Venus and Regulus grow closer each evening.

8 Jul
As the sky darkens, Venus and Regulus stand side by side, separated by 1 finger-width low in the west.

11 Jul
Regulus sinks rapidly toward the horizon while Venus appears stationary.

15 Jul
Venus is 1.5 fist-widths to the moon’s right low in the west at sunset. Mars is 3 finger-widths to the moon’s upper right, and Saturn is 1 fist-width above.

16 Jul
Mars and Saturn grow closer during the next three weeks, and Venus creeps in from the lower right.

17 Jul
Tonight, magnitude 1.2 Spica is 1 finger-width above the moon, and Scorpius is far to its left.

27 Jul
Tonight, magnitude 0.1 Mercury passes within 0.29 degree of magnitude 1.3 Regulus, making this the year’s closest planet-first magnitude star appulse. They set more than an hour after sunset, so you will have a good opportunity to see this event.

31 Jul
High in the south before dawn, Jupiter is 3 finger-widths below the moon. Tonight, Mars and Saturn pass within 1 finger-width, with magnitude 1.5 Mars to the lower left of magnitude 1.1 Saturn.

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August

1 Aug
Near the western horizon at sunset, Mars is 1 finger-width to Saturn’s lower left, and Venus is 3 finger-widths to the lower right.

9 Aug
Mars, Venus and Saturn form a tight triangle. Watch the drama every night for the next two weeks as Venus closes in and eventually overtakes Mars.

10 Aug
The moon is at perigee, 56.11 Earth-radii away. With perigee occurring less than 15 hours after the new moon, we can expect high tides.

11 Aug
At dusk, you should be able to spot the thin waxing crescent moon just above the western horizon. Mercury is 1.5 finger-widths to the moon’s upper right.

12 Aug
Mars, Saturn and Venus are just above the moon this evening.

13 Aug
The moon is 1 fist-width to the left of Venus, Mars and Saturn. Spica is 3 or 4 finger-widths to the moon’s upper left.

17 Aug
Tonight, Venus is directly below Mars, separated by 1 finger-width. Antares, the red heart of Scorpius, is 1 finger-width to the moon’s lower right.

19 Aug
Tonight, Venus, the goddess of love, passes within 1.9 degrees (1 finger-width) of Mars, the mighty god of war. The waxing gibbous moon is just above the dome of the Teapot constellation, Sagittarius.

26 Aug
Late this evening Jupiter rises shortly after the moon, and they travel across the night sky together, ending up high in the west tomorrow morning with Jupiter 3 finger-widths to the moon’s lower left.

31 Aug
Tonight, magnitude 1.2 Spica is less than 1 degree to Venus’ upper right, and Mars is a little more than 1 finger-width to the upper right. The Pleiades is 3 finger-widths to the left or upper left of the moon high in the south before dawn.

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September

1 Sep
Tonight, Venus, Spica and Mars form a nearly straight line. Spica is a little to the right of the much brighter Venus.

6 Sep
Separated by little more than 1 finger-width, Mars is directly above Spica for the next two evenings. Venus slides off to the left, while Saturn sinks closer to the horizon.

10 Sep
Spica is 2 finger-widths to the crescent moon’s upper right. Mars is nearly 3 finger-widths above or to the upper right of the moon. Venus is 3 finger-widths to the moon’s upper left.

13 Sep
Antares is 1 finger-width to the moon’s left low in the south tonight. Try to spot magnitude 3.1 sigma Scorpii, one-half degree to the moon’s lower left, and magnitude 4.8 omicron Scorpii above the moon.

14 Sep
The moon is above the tail of Scorpius this evening.

21 Sep
In opposition to the sun, Jupiter and Uranus rise at sunset, are on the meridian at midnight, and set when the sun rises. You’ll need binoculars, a clear sky and low light pollution to see Uranus, a faint spot one-half finger-width to Jupiter’s upper left.

22 Sep
Rising an hour before sunset, the moon is followed 30 minutes later by Jupiter, 3 finger-widths to the lower right.

23 Sep
Jupiter is 1 fist-width to the moon’s right tonight and 1.5 fist-widths below at dawn tomorrow. The autumnal equinox occurs at 0309 UT.

27 Sep
Look low in the east late this evening to see the Pleiades
1 finger-width above the moon and Aldebaran 1 fist-width below the moon near the horizon.

29 Sep
High in the south before dawn, Aldebaran is less than 1 fist-width to the moon’s lower right, and Orion is directly below the moon.

use binoculars

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