Jon Spargo

Back in January, the Earth reached a point in its orbit known as perihelion; the point at which it is closest to the Sun. On July 5th, we can celebrate aphelion when the Earth is at its greatest distance from the Sun, some 3.4 percent further from it than it was in January.

Early morning sky-watchers are treated this month to the appearance of tiny Mercury. Passing its greatest elongation from the Sun on the 4th, Mercury climbs higher into the early morning sky reaching its greatest elevation above the horizon on the 9th, while brightening to magnitude -0.3. Thereafter, it begins to sink back toward the horizon losing altitude throughout the rest of July.

Mars and Venus steal the show in early July with the pair hovering just above the west-northwestern horizon. On the 11th, the pair of planets is a scant 0.6 degrees apart. Because Venus, at magnitude -3.9 is so bright, it will dominate the much dimmer Red Planet. To see Mars a pair of binoculars may be needed.

Jupiter and Saturn will continue to dominate the night sky, both being almost directly overhead around 2 a.m. as they continue their westerly progression with Saturn leading the parade. That time will be the best for viewing the two giant planets with small telescopes. Saturn’s rings are still open at a good angle for telescopic viewing.

The Moon will be last quarter on July 1st, new on the 10th, first quarter on the 17th, full on the 24th, and last quarter on the 31st. Looking east-northeast on the mornings of July 7th and 8th, about 30 minutes before sunrise, the waning crescent Moon will be slightly above and then slightly below Mercury. A double treat happens on the 11th and 12th

. First, the waxing crescent Moon will bracket both Venus and Mars. The second treat is the close conjunction of Mars and Venus when the two planets will be only 0.6 degrees apart.
Looking to the southwest on the 24th, about 45 minutes before sunrise, the full Moon will be below Saturn. On the 26th, at the same time, the waning gibbous Moon will be just to the left of giant Jupiter.

Due to COVID-19 restrictions there will not be a first Saturday star party at the Etscorn Campus Observatory.

Clear Skies!

Jon Spargo
New Mexico Tech Astronomy Club
July 2021

Jon Spargo, New Mexico Tech Astronomy Club