Northern Hemisphere gazer's guide
July 3: This is the month to look for the very early crescent moon. It should be in good position this evening during early twilight, above the western horizon. The crescent passed below Venus about 8 o'clock this morning (Eastern standard time), so it should be above and to the left of the very bright planet this evening. Look from about half an hour after sunset until the end of twilight to see both Venus and the moon.
Earth is at aphelion, the point in its elliptical orbit where it is farthest from the sun (152,103,500 kilometers, or about 94,513,000 miles).
July 4-5: The star near the crescent moon on these nights is Regulus, in Leo. The moon moves from right to left past Regulus from the evening of the 4th to the 5th.
July 7: The very bright planet Jupiter is to the moon's right this evening, and the first- magnitude object above Jupiter is Saturn. Spica, in Virgo, is to the left and higher than the moon, and about as bright as Saturn. Jupiter is still slightly west of Saturn, but moving slowly to the east (left) below it.
July 12-13: The bright reddish star near the moon is Antares, in Scorpius. The moon is west of the star (to the right) on the 12th, east of it on the 13th.
July 14: Mercury is at greatest westerly elongation, its greatest distance to the right (west) of the sun. Ordinarily, this places the planet in the best position to be seen as a morning star. But this month's is notm a favorable elongation. The planet rises so late and remains so low that daylight obscures it before it can be seen.
July 16-17: A partial lunar eclipse occurs tonight, visble throughout North America except the far north. A lunar eclipse occurs when the moon passes through the earth's shadow. Tonight, the shadow first appears on the lower left edge of the moon at 10:24 p.m. EST. The curved shadow moves to the right across the moon, covering a bit more than half its diameter at mid-eclipse, 11:47 p.m., EST, finally leaving the lower right edge of the moon at 1:09 a.m. on the 17th. Times should be adjusted for various time zones and for daylight time. Note that Earth's shadow, as it gradually covers the lower half of the moon, is not black. It actually casts a dusky red light on the moon, the effect of sunlight diverted into Earth's shadow through refraction as it passes through the atmosphere.
July 20-21: Look above the waning gibbous moon these nights for the Square of Pegasus, four stars very similar in brightness forming a large square on the sky. On the evening of the 20th, the moon passes through the "western fish" of Pisces, just below the center of Pegasus. On the night of the 21st it passes just above the vernal equinox, very nearly in line with but south of the left side of the "Square."
July 27: The moon is at perigee, nearest Earth.
July 28: The Delta aquarid meteor shower reaches maximum this morning. You may see up to 20 shower meteors per our from this weak, broad stream for two or three days before and after the 28th. Look in the morning from 2 a.m. on. Remember, with meteor showers, patience pays off.
July 30: The last episode of the "triple conjunction" between Jupiter and Saturn ends today when Jupiter passes Saturn from right to left. The first conjunction occurred Jan. 14, also when Jupiter moved easterly (to the left) past Saturn. But then Jupier reversed its motion and passed Saturn for the second time, going west, on Feb. 19. Reversing again as it resumed normal easterly motion brings Jupiter past Saturn for the third and last time today. It will be several centuries before the sequence occurs again.
July 31: The third and last eclipse of the year occurs today, a solar eclipse. It is total along a narrow path beginning in the Black Sea, crossing Central Asia, and ending in the Pacific Ocean north of Hawaii. A partial eclipse will occur over a much larger area, including Eastern Europe and most of Asia, Hawaii, Alaska, and northwestern Canada. The eclipse in America (including Hawaii) will be late in the day, endig in some places after sunset.
All month: Venus has been an evening star since early April, but it is only now coming into a position where it can be seen easily. Look for it low in the west-northwest about half an hour after sunset, when its brightness overcomes the darkening twilight. But look early: it sets about two hours after sundown. Some night when you have a clear western horizon, try to watch Venus setting. It often goes through rapid color changes, and it seems much larger.
Jupiter and Saturn continue to put on a good show high in the southwest at dusk, Jupiter brighter than any star in the sky, Saturn very close just above it. The two objects have been near each other since late last autumn, their retrograde motions keeping them from separating very far. Now, both are moving easterly again, and Jupiter, the faster of the two, passes Saturn on July 27 and then begins to separate steadily to Saturn's left.