Outta Sight
This month, I will write more about things and events we can’t see more than what we can. That is how things go with the sky- a great event can take place when skies are cloudy, or the Earth could be turned the wrong way at the time so that our part of the world can’t see it.
Two planets are completely invisible in August- Venus and Mars. In both of their cases, they are passing on the far side of the Sun as seen from Earth, and are lost in the solar glare. Mars will slowly emerge into the predawn sky this fall. Like racers that start off on the opposite sides of the track, Earth, the faster racer, will slowly catch up to Mars, but it will take a long time. Mars will appear to slowly rise earlier and brighten up, outshining all stars in the night sky at its peak near October 13, 2020. Venus is a faster racer, and will begin to catch up to Earth, appearing in the sky at dusk around the end of September. After an inconspicuous start, hovering in bright twilight just after sunset, Venus will be a brilliant “evening star” from late fall through most of next spring, before it passes almost between Earth and Sun next June 3.
The Earth (blue), Mercury (green), Sun (yellow), Venus (white), and Mars (red) in early August, in this image used with permission from Heavens-Above.com. The planets will move counter-clockwise around the Sun, with Mercury and Venus moving faster than the Earth and Mars slower. The Earth also rotates counter-counter clockwise in this view, so Mercury would appear to rise just before the Sun and Mars set just after it in early August, but all are so much in line that they will be very difficult to see.
The biggest event of August will be the Perseid Meteor shower, peaking this year before dawn on the morning of August 13. The Perseid shower is not necessarily the strongest of all meteor showers, but it peaks during the summer when it is comfortable outside to go out and look. Occurring every year when the Earth intersects the orbit of Comet Swift-Tuttle, if you out go to a dark sky country location and skies are very clear, you can see as many as one Perseid per minute at the peak. If you live near the city, MUCH FEWER meteors will be seen, but it still is worthwhile to lay out in a camping chair or sleeping bag and watch. The radiant point in the sky where the Perseids appear to come from does not get high in the sky until well after midnight, so watching early in the evening reveals few meteors.
This year, unfortunately the almost Full Moon will greatly diminish the Perseids. Only the brightest meteors will pierce the brilliant moonlight until the Moon sets, just an hour or two before dawn. On the morning of Tuesday, August 13th, there is a small window from around 3:30-5 am St. Louis time where there is little moonlight and the morning twilight has not yet become too bright. On the previous morning, the 12th, there won’t be as many meteors, but the window is bigger, from about 2:30-5 am.
Many people, including myself, will probably give it a pass this year with it being a work day and the shortened time frame, but will there anybody out there braving the very early morning hours and mosquitoes to peek at the Perseids? Send me a note at richard_fefferman@nps.gov and let me know.
A Perseid meteor passing through the constellation Orion. Photo by the author.
Gateway Arch National Park will complete its celebration of the Moon landing with a special program on August 17 at 8 pm. Washington University scientist Dr. Ryan Clegg-Watkins will give her thoughts on “Fifty Years” since Apollo in the Park’s Education Classroom, on the lower level inside the new West Entrance of the Arch Visitor Center. Learn about the past, present, and future of lunar exploration in the free program. If skies are decently clear, there will be free telescope viewing led by volunteers from the St. Louis Astronomical Society out on the West Entrance Plaza until 10 pm. The almost Full moon, Jupiter, and Saturn will be seen. Call 314-655-1708 the afternoon of August 17 for an update on the telescope viewing- Dr. Clegg-Watkins’ talk will take place regardless of the weather.