SKY GUIDE: This map represents the night sky as it appears over Maine during July. The stars are shown as they appear at 10:30 p.m. early in the month, at 9:30 p.m. at midmonth, and at 8:30 p.m. at month’s end. Saturn is shown at its position later in the month. To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom. Sky Chart prepared by Seth Lockman
The month of July is named for Julius Caesar. This is always the first full month of summer for us in the northern hemisphere. The nights are already getting longer again since the summer solstice. There will be many interesting highlights this month, even though it won’t quite be able to match all the drama that occurred last month.
The great morning planetary lineup in order from Mercury to Saturn is still with us for the first week of the month, but it will spread out over 118 degrees from its most closely packed arrangement of just 91 degrees back in early June. Make sure you see it at least once early in July if you have not already seen it in June. Also try to photograph it if at all possible. This will not happen again until 2040, but then the last two planets, Uranus and Neptune will not be included among the other five as they are now.
The other highlights include some nice lunar conjunctions with all the planets in the morning sky starting on July 16 with a nearly full moon and Saturn and lasting right through July 26 when the moon will have faded to a slender waning crescent as it finally catches up with Venus.
The remaining highlights include the opposition of an asteroid named Aquitania in Ophiuchus the Serpent Bearer and Comet C/2017 K2 (PanSTARRS) will also be visible in that same constellation just a little farther north of Aquitania and on the other side of M14, a nice globular star cluster containing about a quarter of a million stars located about 30,000 light years away.
Then the first good meteor shower since early May will peak on the morning of July 30. That is the Southern Delta Aquarid shower. You can only expect about 12 meteors per hour emanating from western Aquarius, near Capricorn. People in the southern hemisphere will see about twice as many since Aquarius will be higher in the sky for them. They are caused by Comet 96P/Machholz. That comet, along with near earth asteroid EH1 which causes the Quadrantid meteors in early January each year, can be traced back to a comet that broke up about 9,500 years ago.
The great parade of planets marching in perfect order now begins a little earlier each night as Saturn starts the month rising at 11 p.m. and ends it by rising two hours earlier. The ringed planet will reach opposition next month on Aug. 14 when it will rise exactly at sunset.
Then there will be a gap of about two hours before Jupiter will rise in Cetus the whale. The King of the Planets will begin its own retrograde motion on July 29 and reach opposition on Sept. 26.
Then there is a gap of about one hour as Mars will begin the month rising at 2 a.m. in Pisces. Notice that all three of these superior planets will be getting slightly closer and brighter and larger in our sky with each passing morning. The red planet will not reach opposition until Dec. 8 when it will be just 38.6 million miles away, about twice as close as its average distance. Unlike the other superior planets which reach opposition every 13 months, Mars only reaches opposition every 26 months.
Now we get to the inferior planets, inside the earth to the sun. Venus rises at 3:45 a.m. to begin the month just above Aldebaran in Taurus the Bull. Then the other inferior planet, Mercury, finally finishes this great parade as it rises in the east just 45 minutes before sunrise. Mercury will drop out of this great lineup by the end of the first week of this month, only to reappear in the evening sky by July 25.
The last two planets in our solar system, Uranus and Neptune, will also line up in order, but only with each other and not with the other five planets we just covered. Uranus will show up about evenly spaced between Venus and Mars and Neptune is located between Jupiter and Saturn, but much closer to Jupiter. You will need at least a small telescope to see those two last planets in our solar system. Uranus glows with a subtle greenish light and Neptune is a pale blue.
It is always nice to see at least one or two planets and the moon at the same time to get a much better sense of our ecliptic plane in space and how we are really orbiting the sun. Now we can see all seven of our planets at the same time. The moon will always pass fairly near any given planet once a month, but it is particularly impressive when they are all nicely lined up and you can get a good sense of its speed and its shape along the ecliptic with so many markers on its path.
The Southern Delta Aquarid meteor shower will start in mid July when the moon begins to point out all of our planets. It will peak during the morning of July 30. These meteors tend to be fainter than the Geminids and other meteors because they are smaller particles of dust than other showers create and they are hitting our upper atmosphere at slower speeds, only about 25 miles per second. The Perseids are much faster at 40 miles per second. By comparison, the earth is always moving around the sun at 18.6 miles per second, or exactly 10,000 times slower than the speed of light.
JULY HIGHLIGHTS
July 1: Venus passes just one degree north of Aldebaran in Taurus this morning.
July 3: In 1935, Harrison Schmitt was born. He, along with Gene Cernan, where the last two humans to ever walk on the moon with Apollo 17 on Dec. 11, 1972.
July 4: Earth is at aphelion or farthest from the sun for the year at 94.5 million miles today. That is only 3.4% farther than it was at perihelion on Jan. 4.
July 6: First quarter moon is at 10:14 p.m. Isaac Newton published his Principia in 1687.
July 7: The Mars Opportunity Rover was launched in 2003. It enjoyed great success and discovered many unexpected things on Mars over 14 years, along with its twin, the Spirit Rover, far outlasting its expected life of only three months.
July 10: The waxing gibbous moon is near Antares in Scorpius this evening. Antares, similar to Betelgeuse, has a discernible orange hue. It’s about 500 light years away and about 700 times the diameter of our own sun.
July 12: Buckminster Fuller was born in 1895. He was known as the planet’s friendly genius and invented many useful things including the geodesic dome.
July 13: Full moon is at 2:38 p.m. This is also known as the Hay or Thunder Moon. Venus will pass very close to M1, the Crab Nebula in Taurus this morning.
July 16: The moon passes near Saturn.
July 17: The moon passes near Neptune this morning. The first photograph of a star was taken in 1850.
July 18: India became the seventh nation to launch its own satellite in 1980.
July 19: The moon is near Jupiter this morning.
July 20: In 1969 the first humans landed on the moon – Neil Armstrong and Buzz Aldrin with Apollo 11.
July 21: The moon is near Mars this morning.
July 28: The Southern Delta Aquarids peak this morning.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.
Send questions/comments to the editors.
