Monthly Archives: August 2021

32 inch Cassegrain Project

Planets of the Month: September 2021

By Erich Karkoschka

Mercury is visible about 15 degrees to the lower right of Venus until September 21st. It is so low that it remains close to the limit of visibility (use extreme caution to avoid looking at the Sun). It passes Spica on the 21st. However, Spica definitely requires binoculars since it is one magnitude fainter than Mercury.
Venus is the obvious evening star until it sets after 8 pm. It passes Spica on the 5th. Venus is slowly brightening towards its best in December.
The two giant gas planets shine in the southeast during dusk. Their distance slowly decreases from 18 degrees at the beginning of September to 15 degrees at the end. They transit around 10 pm, perfect for telescope or binocular viewing.
The Galilean satellites’ orbits are very close to edge-on this month, so that conjunctions of two satellites become very close. The best shadow transit occurs on the 5th starting at 7:45 pm when the dark disk of Ganymede is already close to the center of Jupiter’s disk, so that two dark spots will be visible. The same occurs 7 days later, although Ganymede’s transit does not start until 9:20 pm with its shadow joining at 11:47 pm. Also, on the 17th, Callisto’s shadow can be seen until 8:13 pm.
Neptune comes into opposition in the constellation Pisces on September 14th. Uranus is one constellation further east in Aries.
The Moon might be just barely visible on September 7th (one day past New Moon), 10 degrees to the right of Mercury. Even if Mercury is difficult to spot, you will see it before you see the Moon. The three day old Moon has a beautiful pairing with Venus on September 9th. Three days later it passes Antares.
32 inch Cassegrain Project, Astronomical Events, General Astronomy, Solar System

Planets of the Month: AUGUST

By Erich Karkoschka

Mercury will start its visibility at dusk, but will never get very obvious. It remains close to the Sun.

Venus is the evening star during dusk. It passes Beta Virginis on the 13th at only 7 arc minutes in distance, similar to the distance between Jupiter and Saturn during the last winter solstice. But the faintness of the star will probably require binoculars to see it.

Saturn comes to opposition on August 2nd, when it rises at sunset. Around that time, its rings are very bright as compared to the planet.

Jupiter also comes to opposition this month on August 22nd. The evening before, the Full Moon will be right next to Jupiter.

On the evening of August 18th, the Moon occults Nunki, the second brightest star of the teapot asterism in Sagittarius. In Nogales, it will last from 7:47 to 8:01 pm, but in Tucson the Moon will not quite make it, although it will get very close to the star. In between there is a grazing occupation which is rare for such a bright star to get so close to us.
August is meteor month. The Perseids will peak on the night of August 11-12 when the Moon is next to Venus which sets early. It cannot be much better than that!! Look toward the east late evening or early morning toward the constellation Perseus.