July 16, 2022: Mercury is at superior conjunction today. Four bright planets shine before daybreak. The Milky Way shines during summer evenings.
by Jeffrey L. Hunt
Chicago, Illinois: Sunrise, 5:30 a.m. CDT; Sunset, 8:23 p.m. CDT. Check local sources for sunrise and sunset times for your location.
Mercury is at its superior conjunction. It is in a line with Earth and the sun, with the sun in the middle. From Earth, the sun’s glare makes observing the planet impossible under normal observing conditions. The planet speeds into the evening sky, but has a poor showing next month. It sets during brighter twilight. Mercury’s other solar conjunction is known as inferior conjunction, when the speedy planet is between Earth and the sun. Mercury then emerges into the morning sky.
The bright moon, 90% illuminated, is about one-third of the way up in the sky above the south-southwest horizon before daybreak, 7.7° to the left of Saturn.
Through a binocular, the asteroid 4 Vesta is in the upper left of the field of view when the moon is to the lower right. The starfield contains dim unnamed stars, although they have catalog numbers.
The asteroids are irregularly shaped masses made of rock and metal. These rocks revolve around the sun between the orbits of Mars and Jupiter. The region, known as the asteroid belt, is not full of orbital debris. Several spacecraft have successfully passed through the belt without interaction with any materials.
Vesta was the fourth asteroid observed, first sighted in 1807. It is irregularly-shaped and about 500 miles long, resembling a potato. It is the second largest body in the asteroid belt after Ceres.
NASA’s Dawn spacecraft studied Vesta for over a year beginning in July 2011. This asteroid is covered with impact craters and close-ups can be mistaken for the moon. These indicate many collisions with smaller bodies.
Saturn is retrograding in eastern Capricornus, near the star Deneb Algedi. The planet is moving slowly, but its change against the starry background is evident. It is 1.3° to the upper right of the star this morning and slowly passing it.
Farther eastward and high in the south-southeast is bright Jupiter. It is slowly moving eastward in Cetus. It begins to retrograde at month’s end.
Mars, marching eastward in Aries, is nearly 30° to the lower left of Jupiter. The Red Planet is passing the constellation’s brightest star, Hamal – meaning “the full-grown lamb.” Their gap is nearly 12° as the bright stars are far from the ecliptic when the planets appear to move against the background stars.
The brightest planet and star in the sky this morning is Venus. Now east of the Bull’s horns, the Morning Star is in the club of Orion for the next few mornings before stepping into Gemini.
Taurus is getting easier to see as it is higher in the sky each morning and noticeably higher each week. The reddish star Aldebaran is joined by the Hyades star cluster to make the Bull’s head. The Pleiades cluster is on the Bull’s back.
Mars is marching generally toward the Pleiades. This morning, the Red Planet is over 20° to the right of the stellar bundle. Mars passes the cluster in about a month.
After sunset on moonless nights beginning now at mid-month and occurring each month through September when a bright moon is not present, the Milky Way – the rim of our galaxy arches eastward from the southern to the northern horizon line. It leaves the southern horizon, between Scorpius and Sagittarius. This region this thought to be the center of the galaxy and it is the direction where there is likely a galactic black hole that provides the gravity to hold the Milky Way together. The band of light extends through the Summer Triangle consisting of the stars Vega, Altair, and Deneb.
To see the delicate band of light, a dark location – free from outdoor lighting – is necessary. Scan the Milky Way with your unaided eyes and through a binocular. Bunches of stars, whisps of gasses, and seemingly voids are visible.
Seeing the Milky Way becomes challenging every year as more and more streetlights, parking lot lights, and “security lights” are installed. Much of the light is not directed downward, but horizontally and upward.
The famous “Earth at Night” photo shows what our planet looks like during the nighttime hours. Lights from major metropolitan areas are easily identified. In North America, city lights outline Lake Michigan, Lake Erie, and Lake Ontario. Cities that are along interstate highways act like a map of the roadways. Some Earth regions are dark at night like the interior South America, northern North America, Africa, Australia, and Asia. Note the highways that extend eastward from Moscow into the interior of Russia. Unless we are trying to communicate our presence in space, this is wasted energy. With the demands and costs of current energy shortages, wasted outdoor nighttime lighting must be part of the conversation.
March 4, 2023: Venus steps away from Jupiter after sunset. The evening gibbous moon is in the eastern sky, above Regulus. Mars marches eastward against Taurus.Keep reading
March 3, 2023: Two nights after their spectacular conjunction, Venus and Jupiter are in the west-southwest after sundown. The evening gibbous moon is with Cancer, between Regulus and Pollux.Keep reading
March 2, 2023: Venus opens a gap on Jupiter in the west-southwest after their conjunction last night. The moon is near Pollux after sundown. Mars marches eastward against Taurus.Keep reading