The Earth is at aphelion, its greatest distance from the Sun, on July 3rd. It will be slightly over 3 million miles farther from the Sun than it is on its closest approach on Jan. 4 this year.

It may surprise some that it is much colder when we are closer to the Sun but such a small difference, given the fact that Earth’s average distance from the Sun is nearly 93 million miles, plays no significant role in the amount of solar energy that reaches us. What determines the seasons is not distance but tilt.

The Earth’s axis of spin, which points towards Polaris the pole star, lies 23.5 degrees from the vertical. North America is tilted favorably towards the Sun in the summer and away from it in the winter.

Thus we receive more of the Sun’s rays in the summer months, and the fact we are a bit further away does not matter.

Focus on the planets

Mercury may be spotted low in the west 40 minutes after sunset during the opening days of July and then disappears to reemerge in the morning twilight at month’s end.

Venus is low in the east-northeast where it shines brilliantly in the pre-dawn sky. On July 2nd, Venus lies to the upper left of Aldebaran, the ‘red eye of the bull.’

Mars starts the month on the western horizon at sunset where it may be seen to the upper left of its much brighter companion Saturn. The bright star to the upper left of Mars is Regulus, which the Red Planet will brush by on July 21.

Jupiter reigns alone high in the southwest as darkness falls where it remains in view until after midnight. Jupiter’s banded surface and the movements of its four major moons will provide plenty of viewing opportunities.

Saturn is also in the west shortly after sunset sandwiched between Mars to the upper left and Mercury to the lower right as July opens. It comes up about an hour after the Sun. None of the three planets are particularly prominent.

Uranus in Aquarius and Neptune in Capricornus appear as greenish and bluish disks respectively. Both are well within the range of good binoculars but you may need star charts to locate them.

Pluto is high in the southeast at nightfall. This uninspiring planet has suddenly made headlines with two new moons, Nix and Hydra, joining its known one Charon. For a planet not much bigger than a large asteroid, the presence of three moons is indeed a puzzle.

July events

1 Sunrise, 4:53 a.m.; sunset, 8:25 p.m. The moon is at apogee or farthest distance from the Earth. If you plan to be up about an hour before sunrise, look to the east where you can see Venus tucked among the stars of the Hyades with Aldebaran to the near lower right.

2 Today is the midpoint of the year at 1:00 p.m. Be sure to look to the western horizon about 40 minutes after sunset tonight where Regulus, Mars, Saturn, and Mercury form a descending line from left to right.

3 Moon in first quarter, 12:36 p.m. The Earth is at aphelion or farthest distance from the Sun at 7 p.m. today. It is about 3.4 percent farther away than at perihelion that occurs in January.

4 Celebrate the nation’s birthday by checking out the southwestern horizon shortly after dark. Among the fireworks you should see the moon with Jupiter to the upper left and Spica immediately to the lunar right.

11 Full moon, 11:03 p.m. The full moon of July is known as the Hay Moon, Grain Moon, or Thunder Moon.

13 The moon is at perigee, or nearest approach to the Earth, today.

15 The ‘Summer Triangle’ consisting of Altair in Aquila the Eagle, Deneb in Cygnus the Swan, and Vega in Lyra the Lyre is prominent in the eastern sky after sunset.

17 Moon in last quarter, 3:13 p.m.

20 The Sun enters the constellation of Cancer on the ecliptic. If you are up and about in the middle of the night, look to the east around 3 a.m. for a view of the moon passing through the Pleiades star cluster. On this date in 1969 the first astronauts, Neal Armstrong and Buzz Aldrin, walked on the moon.

21 Mars is extremely close to Regulus in the west about a half hour after sunset.

22 The Sun enters the astrological sign of Leo but, astronomically, has just entered Cancer. Look to the northeast at dawn to see Venus just beneath the waning crescent moon.

25 New moon, 12:31 a.m.

27 Faint Mars is sandwiched between the thin crescent moon to the upper left and Regulus to the lower right at dusk on the northwest horizon.

28 The peak night for the Delta Aquarid meteor shower. Look south at about 4 a.m. for a stream of 15-20 meteors per hour radiating out of the constellation of Aquarius.

29 Moon at apogee for the second time this month.

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

Send astronomical queries to Clair Wood at cgmewood@aol.com or care of the Bangor Daily News, Style Desk, P.O. Box 1329, Bangor, Maine 04402.