You are hereTHIS MONTH'S SKY - August 2010
THIS MONTH'S SKY - August 2010
THIS MONTH'S SKY
Celestial Events -- August 2010
THE GATHERING IN THE WEST REACHES A CLIMAX
| For the last few months we have been treated to Venus, Mars and Saturn in the western sky at dusk. Over time we have seen Mars closing in on Saturn, and Venus in turn approaching both Mars and Saturn.
As August begins Mars passes 2° below Saturn. If you have a wide-field telescope, you may be able to see both planets in the same field. Binoculars will show them -- you should be able to see the color difference between yellowish Saturn and orangeish Mars. Brilliant Venus is 7° from the other two planets. If you look carefully you may spot Mercury 12° lower left of Venus (binoculars may be needed). After the first week in August, Mercury will become very difficult to see as it becomes fainter. |
 Mercury, Venus, Mars, Mercury 9 PM August 1-31 |
By the 5th Venus is within 3½° of Saturn and 6° from Mars. Two nights later the tightest grouping of the planets occurs, as all three fit within a 5° circle. The next night Venus and Saturn are closest, less than 3° apart!
On August 11 the Moon enters the picture, 3° below Mercury. The next evening it is about 7° below the three other planets. Venus passes below Mars by less than 2° between the 17th and 20th.
Venus is 1° below the bright star Spica on the 30th. As the month ends Saturn is 17° below right of Mars and 20° below right of Venus, an indication of how fast Mars and Venus move compared to Saturn. At this time Mars is 4° upper right of Venus.
By now almost all the interesting activity of the three planets has concluded, and they will be swallowed up by the Sun. But we have a replacement -- Jupiter will be at opposition next month!
NEPTUNE AT OPPOSITION
| The planet Neptune is at opposition to the Sun on August 20. On that day it is "opposite" the Sun, up all night, rising at sunset and setting at sunrise. Neptune is currently retrograding (moving from east to west with respect to the stars) as all outer planets do when nearing opposition. As a result it moves from Aquarius back into Capricornus on the 13th.
Neptune is in a rather dim portion of the sky. It is best found by first finding the region between Iota (ι) Aquarii (magnitude 4.3) and Mu (μ) Capricorni (magnitude 5.1). See Figure 1 to the right. Neptune itself will be about magnitude 7.8 this month. Figure 2 shows close-up positions of Neptune at five-day intervals. |
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Figure 2 |
Click to get sky charts and a description of the sky for this month.
PLANETS IN AUGUST
MERCURY is in the evening sky all month. Although it is up for most of August (its greatest elongation on the 6th is 27° from the Sun), it is very low. Mercury is best seen early in the month when it is brightest (magnitude +0.1).
VENUS (magnitude -4.3 to -4.6, diameter 19.9" to 27.9", phase 58% to 42% lit) dominates the planets in the west at dusk. It passes Saturn on the 7th, is closest to Mars on the 18th, and passes Spica on the 31st. It is at greatest eastern elongation from the Sun (46°) on the 19th. See above for more information.
MARS (magnitude +1.5, diameter 4.7" to 4.4") passes Saturn as August begins. In turn it is passed by Venus on the 18th. See above for more information.
JUPITER (magnitude -2.7 to -2.9, diameter 45.8" to 49.1"), moving retrograde in Pisces, rises about 10:30 PM on August 1 and about 8:30 PM on August 31. Late in the month it rises just after the planets in the west have set. Jupiter will be at oppostion on September 21.
SATURN (magnitude +1.1 to +1.0, diameter 16.4" to 15.9") is in western Virgo. Mars has just passed Saturn as August begins, and Venus passes the ringed planet on the 7th. See above for more information.
URANUS (magnitude +5.8, diameter 3.7") is retrograding in Pisces. Locate it from nearby Jupiter. On the first day of the month the two planets are 3° apart, closing to 1¾° during August. Uranus will be at opposition on September 21, the same day as Jupiter.
NEPTUNE (magnitude +7.8, diameter 2.4") is in western Aquarius, retrograding into Capricornus this month. It is at opposition on August 20. See above for more details.
PLUTO (magnitude +14.0, diameter 0.1") is still in western Sagittarius.
The MOON is at last quarter on August 3rd and full on the 9th. Two days later it is just below Mercury (use binoculars). On the 12th the Moon is below the grouping of Mars, Venus and Saturn (left to right). The next two evenings the Moon passes below Spica. It is at first quarter on the 16th, and next evening is less than 2° to the upper left of Antares. Full moon is on the 24th.
THIS MONTH'S EVENTS
(Times in EDT)
| AUGUST 1 | Mars is only 2° lower left of Saturn. They are 7° upper left of bright Venus. |
| August 3 | Last Quarter Moon at 12:59 AM. |
| August 4 | The Pleiades are 4° lower left of the Moon this morning. |
| August 6 | Mercury is at greatest eastern elongation (27°) from the Sun. |
| AUGUST 7 | Venus passes 2¾° below Saturn this evening. At the same time it is a little less than 5° from Mars to the upper right. |
| AUGUST 9 | Venus is 3° below left of Saturn and 4° below right of Mars. |
| New Moon at 11:08 PM. | |
| August 11 | A thin crescent Moon is 3° below Mercury in the twilight. Use binoculars. |
| August 12 | The Moon is well below Saturn, Venus and Mars. Venus is closest, 7½° away. |
| AUGUST 12 | The Perseid meteor shower peaks tonight. |
| August 16 | First Quarter Moon at 2:14 PM. |
| August 17 | The Moon is only 2° above the bright star Antares. |
| AUGUST 18 | Venus is closest to Mars tonight, a little less than 2°. |
| August 19 | Venus is at greatest eastern elongation (46°) from the Sun. |
| AUGUST 20 | Neptune is at opposition to the Sun and up all night. |
| August 24 | Full Moon at 1:05 PM. |
| August 27 | The Moon is 6½° above Jupiter this morning. |
| August 31 | Venus is only 1° south of the bright star Spica. |
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