Named after Augustus Caesar, August is the last full month of summer, and while the heat has arrived, don’t let that deter you from enjoying and learning about the many wonders of the night sky.

Among this month’s highlights – Jupiter and Saturn continue to rule the evening and night sky, Mercury makes a nice appearance in the morning sky, the Perseid meteor shower peaks, three asteroids are at opposition, and the first in a string of fairly bright comets arrives that will last for more than a year.

Jupiter now rises 2 hours before sunset, so it is already nice and high in the southwestern sky by the time it gets dark. The king of the planets was at its best two months ago, and it will end its retrograde, or westward, motion toward Antare, the red super giant star in Scorpius, on Aug. 11, just one day before the Perseid meteor shower peaks. It will continue on its normal, direct or eastward motion against the fixed background of stars for the next eight months.

When looking at this brilliant planet in our sky, remember that we sent a mission to Jupiter – named Juno – that started orbiting the planet 2 years ago in highly elliptical 53-day orbits. Juno has taken thousands of amazing pictures that help us to understand this giant gas planet a little better. We learned that Jupiter has about five times more oxygen than the sun, and it has liquid water above its deepest clouds. It also has an interior magnetic field that changes over time. Juno is scheduled to complete 37 orbits, probably in July of 2021. That’s just a few months after the James Webb space telescope is finally scheduled to launch after many postponements. This telescope will have to work perfectly the first time, since it will be going into orbit at the L 2 Lagrangian point about 1.5 million miles away from Earth.

Saturn was at its best last month and is still very visible in the southern evening sky, 30 degrees or one constellation to the east, or left, of Jupiter by the time it gets dark. The ringed planet will remain in retrograde motion until the middle of next month. Notice that it appears to glow with a soft golden light and is about 10 times fainter than Jupiter.

Through a telescope, you will see that Saturn’s rings are tilted at 25 degrees to our line of sight, also that the north Polar Regions appear duskier gray and the temperate regions appear more yellowish. You should be able to see at least five of its 62 moons in an average telescope. Titan, the largest one, is bigger than both Mercury and Pluto. You can see the four large Galilean moons of Jupiter’s 79 moons with just a good pair of binoculars. Pluto is just 6 degrees, or three fingers at arm’s length, to the east of Saturn, but it is 400,000 times fainter and requires a 10-inch telescope to see it.

Mercury is the only other planet visible now. It will make a good appearance in the morning sky after the first week of the month. Notice that it will form a nearly straight line with Castor and Pollux in Gemini, not too far from where it was when Mercury was still an evening planet located very close to Mars. At only 3,000 miles in diameter, our first planet is a dynamic and interesting cratered world that has the most iron in its molten core of any planet in our solar system and also the largest temperature range –  over 1,000 degrees – between day and night. It will reach 800 degrees on the side facing the sun and -300 degrees on the night side, because it has no atmosphere, unlike Venus, which maintains a steady 800 degrees everywhere.

One year on Mercury lasts 88 Earth days and one day on Mercury lasts 59 Earth days, meaning that it rotates very slowly, only 6 miles per hour, or a comfortable jogging speed. Only Venus rotates slower at 4 mph. Our moon also rotates quite slowly, at 10 mph, so one day lasts a full month.

When you look at this little planet in our morning sky that is smaller than two of our solar system’s moons, Ganymede and Titan, be aware that we launched a mission there last October named BepiColombo, after the Italian scientist who first figured out how to use gravity to assist for interplanetary maneuvering. Complicated orbital mechanics and the strong gravitational force of the sun mean it will not arrive until December of 2025.

The Perseid meteor shower will peak on Monday night the 12th into Tuesday morning the 13th. Unfortunately, the full moon is only two days later ,so you will have just a small window of 1 hour before dawn after the moon sets. Caused by Comet Swift-Tuttle, this shower usually produces at least 60 meteors per hour, but you won’t see that many this year. Even so, I encourage you to try to catch some bright bolides streaking through our sky.

An asteroid named 15 Eunomia will reach opposition in Aquarius the same night that the Perseids peak. It will reach 8.2 magnitude, or about seven times fainter than anything that you could see without optical aid. Two other asteroids, Psyche and Laetitia, will also reach opposition this month, on the 6th and the 16th, respectively.

We had a lucky string of six or seven fairly bright comets, about one per month, that ended earlier this year. A new string of ninth magnitude or brighter comets starts next month and lasts for more than a year. This month, with a good telescope, we can see 11th magnitude comet Africano near the Big Dipper.

The new moon caused a total solar eclipse over South America. Then, on July 16, our shadow was projected onto the moon to create a partial lunar eclipse. It was exactly 50 years to the day from when we successfully launched to the moon and four days before humankind landed there for the first time ever. It was as if the sky were actively helping us celebrate the 50th anniversary of one of humankind’s greatest achievements.

 AUGUST HIGHLIGHTS

Aug. 1: Maria Mitchell was born on this day in 1818. She was America’s first female astronomer and the first American scientist to discover a comet. Mitchell also did a lot for the advancement of women in science.

Aug. 3: The Messenger spacecraft was launched to Mercury in 2004.

Aug. 4: The Phoenix mission was launched to Mars to land near its North Pole in 2007.

Aug. 6: The Curiosity Rover was launched to Mars in 2012.

Aug. 7: First quarter moon is at 1:31 p.m.

Aug. 9: The moon passes 2 degrees north of Jupiter this evening.

Aug. 12: The moon passes less than 1 degree south of Saturn this morning.

Aug. 13: The Perseid Meteor shower peaks this morning.

Aug. 14: Venus is in superior conjunction with the sun and will not become visible again for two more months.

Aug. 15: Full moon is at 8:29 a.m. This is also known as the Sturgeon, Green Corn or Grain Moon.

Aug. 23: Last quarter moon is at 10:56 a.m.

Aug. 25: Mars is at aphelion or farthest from the sun this evening. It will not be visible again for a couple more months. The Spitzer infrared telescope was launched on this day in 2003. This was one of the family of four space telescopes that cover a large spectrum of light from gamma ray to infrared.

Aug. 30: New moon is at 6:37 a.m.

Bernie Reim lives in Wells and is co-director of the Astronomical Society of Northern New England.


Comments are not available on this story.

filed under:

Augusta and Waterville news

Get news and events from your towns in your inbox every Friday.
  • This field is for validation purposes and should be left unchanged.