July, the seventh month, was named for Julius Caesar, who besides being emperor of Rome and conqueror of most of the known world, reorganized the calendar in 45 B.C. The Julian calendar was created to clear up confusion caused by the fact that the Etruscan calendar, then in use, had only 355 days.

Caesar’s corrections, among them the introduction of leap years, proved to be accurate enough that further corrections were not necessary until today’s calendar was created by Pope Gregory in 1582.

Focus on the planets

Mercury may be spotted low in the east-northeast about 40 minutes before sunrise. On July 2, Mercury and Venus have an extremely close conjunction that is readily visible with binoculars. Mercury vanishes from the scene soon thereafter.

Venus is prominent on the western horizon an hour after sunset. The star to the immediate lower right of Venus is Regulus from the constellation of Leo the Lion.

Mars is low in the west-northwest at sunset, where it is situated to the upper right of Jupiter. A telescope will be required to observe the distance-dimmed Red Planet in the bright twilight.

Jupiter is to be found in the west-northwest, where it sets less than an hour after the sun. Jupiter is lost in the sun’s glare by midmonth but gives one final show on the second of the month, when it has a close conjunction with Mars. A telescope or powerful binoculars will be needed to spot the much dimmer Mars in the twilight glare.

Saturn is situated low on the east-northeast horizon about an hour before sunrise. Be sure to see the ringed planet’s close pairing with Mercury on July 2.

Uranus and Neptune are located high in the southeast, among the stars of Capricorn, after midnight. A finder’s chart and telescope will be needed to spot them.

Our celestial neighborhood

In 1967, Beatles John Lennon and Paul McCartney wrote a song titled “Lucy in the Sky with Diamonds.” Although the song had little to do with diamonds in space, it was remarkably prescient in that a report in the May 24 issue of Science says there are strong indications that diamond dust is drifting in the vast reaches of space between the stars.

A group led by Dr. Geoffrey Clayton of Louisiana State University used the ultraviolet camera aboard the Hubble space telescope to examine the light from distant stars. No matter in which direction they looked, a distinctive pattern known to arise only from diamond crystals appeared.

This is not the first indication that microscopic diamonds may exist in space. The Murchison meteorite also was found to contain microscopic diamond crystals. How many diamonds are present in space? Clayton estimates that the Milky Way contains a million trillion trillion trillion carats, that’s 1 followed by 41 zeros grams! Don’t expect to see diamond mining between the stars anytime soon however, for each is so could be seen small it only under a microscope.

July events

1 Sunrise, 4:53 a.m.; sunset, 8:25 p.m.

2 The moon is at apogee, its farthest distance from the Earth, today. Today also marks the midpoint of the year at 1 p.m. daylight-saving time. Don’t forget the close conjunction of Mercury and Saturn during the early morning hours. Moon in last quarter, 1:21 p.m.

6 The Earth is at aphelion, its maximum distance from the sun, at midnight.

7 A thin crescent moon is situated very close to Saturn in the predawn sky. Aldebaran is to their upper right.

10 New moon, 6:26 a.m.

13 Regulus, Venus and the crescent moon form an ascending line, in that order, on the western horizon after sunset.

14 Moon at perigee, or closest approach to the Earth, today.

17 Moon in first quarter, 12:47 a.m.

20 The sun enters Cancer on the ecliptic, 6 p.m.

23 The sun enters the astrological sign of Leo even though, astronomically, it has just entered Cancer.

24 Full moon, 5:07 a.m. The full moon of July is called the Thunder Moon or Hay Moon.

30 Moon at apogee for the second time this month.

31 Sunrise, 5:19 a.m.; sunset, 8:03 p.m.