Sunrise and Sunset Times
From the U.S. Naval Observatory (Eastern Daylight Time)
Sun rises at 5:37 a.m. and sets at 8:34 p.m. on the 1st
Sun rises at 6 a.m. and sets at 8:16 p.m. on the 31st
Moon’s Phases in July
Full “Thunder Moon” or “Buck Moon” on the 9th
New Moon on the 23rd
Stars and Constellations
The sky does not get truly dark until after about 9:30 p.m. on July evenings, but even before twilight fades into night, you should be able to spot high in the south orangish Arcturus, the second brightest star in the night sky (after Sirius) that is visible from most of the United States. Arcturus, which lies in the constellation Boötes the Herdsman, is considered a star of the spring season, but it will remain visible in early evening through October; it sets by 3 a.m. in mid-July. Two other bright stars of spring are getting low in the west by late evening: blue-white Regulus in the constellation Leo, sets by 10 p.m. in mid-July. And similarly colored Spica, located (along with planet Jupiter) in Virgo, sets around midnight. Arcturus, Regulus and Spica form the Spring Triangle, which will gradually descend into the evening twilight as the summer progresses.
Making their appearance above the eastern horizon are the three stars that comprise the Summer Triangle: Vega in the constellation Lyra the Harp, Deneb in Cygnus the Swan and Altair in Aquila the Eagle. Both Vega and Altair are relatively nearby stars, at distances of 25 and 16 light years, while a recent study puts Deneb’s distance at a whopping 2,600 light years. Vega is just slightly fainter than Arcturus and therefore ranks as the third brightest star tha can be seen in the night sky from the majority of the U.S.
Located between the Herdsman and the Harp is the constellation Hercules, which is identified by its “keystone” of four stars. One notable star in Hercules is Ras Algethi (Arabic for the “Kneeler’s Head”), a triple star system lying nearly 400 light years from our solar system.
Moving into view in the south-southeast in early evening is reddish Antares in the summer constellation Scorpius. Antares is a red supergiant and one of the largest stars known, having a diameter nearly 800 times that of the Sun and lying over 600 light years from our solar system. A little later in the evening, the constellation Sagittarius, with its famous “Teapot” asterism, will be rising in the southeast, to the left of Antares.
Naked-Eye Planets in the Evening and Morning Sky
The planet Mercury is visible at dusk especially toward the end of the month when it is at greatest elongation with the Sun (on the 30th). Look for Mercury hovering very low above the northwestern horizon about 30 minutes after sunset; it looks like a yellow star. Binoculars will help pick it out of the bright twilight.
Jupiter maintains its residence within Virgo, resembling a brilliant golden star to the west of the much fainter bluish-white (true) star Spica. Jupiter stands halfway up in the southwest at nightfall in mid-July and remains in fine position for viewing during the first half of the night, setting around 1 a.m. on the 1st and by about 11 p.m. on the 31st. Jupiter will remain in the evening sky for the rest of the summer, getting lower with each passing week.
Saturn, which reached opposition with the Sun last month, continues to be well placed for viewing in July. At around 10:30 p.m. in mid-July, Saturn stands low in the south and resembles a bright cream-colored star to the far left of the orangish true star Antares. Saturn sets after 4:30 a.m. EDT on the 1st and about 2:30 a.m. on the 31st. This month is an ideal time to view Saturn’s rings through a telescope (even a small amateur one) or a pair of high-quality 10×50 or larger binoculars mounted on a tripod.
Venus continues its dominance among both stars and planets in the pre-dawn sky, shining like a majestic yellow star in the east-northeast. Venus rises around 3 a.m., or nearly three hours before the Sun, for most of July.
Mars reaches conjunction with the Sun on July 26 EDT and is not viewable all month. One year from now, in July 2018, Mars will reach its best opposition since 2003, so be patient!
Earth is at aphelion, its greatest distance from the Sun, on July 3, when it will be 3.3 percent farther from the Sun than it was in January. On July 20, the Sun crosses from the constellation Gemini into Cancer.
Information on lunar phases and rise/set times of Sun and planets is obtained from the U.S. Naval Observatory Data Services at usno.navy.mil/astronomy. For more information on the night sky, visit the Widener Observatory Stargazing website at widener.edu/stargazing. A set of free sky maps can be obtained at skymaps.com.