JULY  2002

JULY STAR MAP | STARWATCH INDEX | MOON PHASE CALENDAR

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306    JULY 7, 2002:   Moon on the Run: Part 1

The moon revolves around the Earth in a period of 27-1/3 days, and as it journeys among the stars, it passes near many bright celestial objects which can be easily identified. Presently the moon is several days before its new phase, when it passes between the Earth and the sun and its far side hemisphere is illuminated. This morning (Sunday), Luna was only about 36 degrees to the west of the sun, rising as a thin waning crescent about 2-1/2 hours before sunrise, and visible in the constellation of Taurus, the Bull. If you managed to see it, you may also have noticed a bright star visible just below the moon. That was Aldebaran in the same constellation, an old blotted red giant star about 65 light years from us and normally thought of as a late fall and winter luminary. On Tuesday morning an even thinner horned moon will be only one degree above the planet Saturn. At 5:00 a.m., 40 minutes before sunrise, the moon and Saturn will be only 10 degrees above the brightening ENE horizon, a sighting that will need a very clear sky and an unobscured horizon. Binoculars will certainly enhance your view. For the next three days the moon will be essentially invisible, as it passes and moves to the east of the sun. The moon now becomes a thin waxing crescent visible in the west after sundown. On Friday at 9:15 p.m., look for the moon to be to the right of brilliant Venus which will be rapidly disappearing from the evening sky during the next several weeks. The star to Venus’ right will be Regulus of Leo, the Lion. It is about 78 light years distant, and it has an energy output or luminosity 160 times greater than our sun. The celestial journey of our moon will be continue next week. Check web StarWatch for maps showing the daily position of the moon in the sky.

Journeying Moon: The moon is visible in the east in the morning sky near Aldebaran and Saturn during the beginning of this week and in the west after sunset near Venus by the end of the week. Graphics by Gary A. Becker...

307    JULY 14, 2002:   Moon on the Run: Part 2

If you were to ask a friend where the moon is tonight, you’d probably get a blank stare. The moon, it seems, has little influence upon our daily existence. Yet to prehistoric cultures, the answer would have been readily known. These people literally "lived by the sky," and their largely out-of-door existence precluded an awareness of the moon’s nightly location. This week our moon quest continues. Download a locator map at web StarWatch. As the week begins, our nearest space neighbor is plainly visible as a fattening crescent in the western sky after sundown. It has distanced itself from Venus in the WNW. The moon passes through the spring sky, a region of the cosmos blessed by few bright stars. However, there is a beautiful blue diamond, Spica, which the first quarter moon encounters on Tuesday evening. Spica is the principal star of Virgo, the Virgin, one of the 12 Zodiacal constellations which the sun passes through during its yearly journey through the heavens. The other stars of Virgo are impossible to see from the Valley, but Spica is first rate, a blue giant binary system 260 light years from us. Spica is about 1,300 times more luminous than our sun, while its companion outranks Sol’s splendor by 250 times. Don’t expect to see the pair. The companion races around Spica every four days, separated by only nine million miles. Binoculars on Tuesday will show splendid Spica and the moon in the same field of view. Binoculars on Friday will also help bring out the red in red supergiant Antares at the heart of Scorpius, the Scorpion. The moon will be located above and to the right of Antares which is 12,000 times the sun’s luminosity and 600 light years away. If you were to substitute Antares for the sun, Antares’ surface would stretch past the Earth’s orbit for 30 million miles.

Journeying Moon: The first quarter moon passes blue Spica on Tuesday and red Antares on Friday. Graphics by Gary A. Becker...

308    JULY 21, 2002:   Moon on the Run: Part 3

The last two StarWatch articles have focused upon the moon’s changing position as it orbits the Earth and circles the heavens, using it to find other bright celestial objects that may be nearby. The dates of the major lunar phases are printed right next to this article each day in The Morning Call. In web StarWatch which can be accessed through the URL listed at the bottom of this article, readers can find the precise moments when the first and the third quarter moons happen, as well as the times of full and new moons. Included with web StarWatch at the bottom of the page is a lunar calendar showing the correct phases for each day of the month. As this week begins, the moon is located in Sagittarius, the Archer, just left of the Milky Way’s galactic center. Dust clouds hide the inner region of our galaxy from even the most powerful optical telescopes, but radio telescopes are able to penetrate this ejected "star stuff" created from countless supernova explosions and infer a dense clustering of rapidly moving stars at the galactic center. This is the signature of a massive but fairly inactive black hole. Keep in mind that the powdery radiance from our galaxy’s stars and glowing nebulae is almost never visible anymore, even from suburban Valley locations. If a power outage occurred this week, we would still be out of luck because the brightness of the moon would easily obscure all of the Milky Way’s beauty. The moon is full on Wednesday morning at 3:08 a.m., so look for it to rise just before sunset on Tuesday and a little after sunset on Wednesday. Thereafter, the moon wanders through some really obscure constellations: Capricornus, the Sea Goat on Thursday and Friday; and Aquarius, the Water Bearer on Saturday and Sunday. Late next, week things become interesting.

Journeying Moon: . The moon passes near to the position of the center of our Milky Way galaxy on Sunday and is full early Wednesday morning. Graphics by Gary A. Becker...

309    JULY 28, 2002:   Moon on the Run: Part 4

We have been following the journeying moon, identifying the objects that it passes during its 27-1/3 day trek through the heavens. It takes this duration of time for the moon to return to its same position relative to the stars, which is the moon's orbital period. During this interval the Earth has completed about 1/12th of its orbit around the sun. In order to repeat the same lunar phase alignment, the moon also requires an additional travel time equal to 1/12th of its orbital period or about 2-1/6 days. The cycle of lunar phases, the various shapes that the moon goes through, takes on average about 29-1/2 days, giving us our month (moonth). As this week unfolds, the moon is rising later each evening and moving through the fall constellations of Aquarius, the Water Bearer, Sunday morning; Pisces, the Fish, Monday; Cetus, the Whale, Tuesday; then Pisces again on Wednesday; and Cetus again on Thursday. If this sounds confusing, blame the International Astronomical Union which set the constellation boundaries in 1930. View a map of the moon's changing position at web StarWatch. Thursday, the third quarter moon's straight terminator, the boundary between day and night, points up to the star Hamal in the constellation of Aries, the Ram. View around 4:30 a.m. Hamal, about 66 light years from our sun, should appear yellowish-orange through binoculars. This giant star is near the end of its life. By Saturday, the waning crescent moon is nearly equidistant from the Pleiades, a young star cluster, 400 light years away, and the aged red giant star Aldebaran, 65 light years distant. Both objects are part of the winter constellation of Taurus, the Bull, a harbinger of seasonal changes in the making. The moon is new again on August 8th.

Journeying Moon: The moon's terminator lines up with Hamal on Thursday and passes between the Pleiades star cluster and the star Aldebaran by Saturday. Graphics by Gary A. Becker...