CVIndependent

Wed11222017

Last updateWed, 27 Sep 2017 1pm

28 Jul 2017

August Astronomy: On Monday, Aug. 21, the Much-Anticipated Solar Eclipse Will Take Place—Nine Days After the Perseid Meteor Shower's Peak

Written by 

The summer of 2017 marks the 54th anniversary of my first successful expedition to observe a total solar eclipse.

The date was July 20, 1963, when our carload of astronomy graduate students from the University of Michigan made the long drive from Ann Arbor to the path of totality in Quebec. Cumulus clouds parted—and we had a spectacular view.

When it came to astronomy, I was hooked.

I hope some of you have a chance to make the journey to the August eclipse’s path of totality. This event is part of the Saros series—same as the eclipse I saw in 1963. These eclipses are spaced at intervals of 18 years plus about 11 1/3 days, and after three Saros intervals—called an Exeligmos—a solar eclipse very much like the one in 1963 happens again, within a similar track through our region of the world, only farther south. Instead of Alaska through Canada and Maine as in ’63, the ringside seats on Monday, Aug. 21, will be in Oregon to South Carolina, making this eclipse an exclusively American event.

Even if you can’t go to Oregon or another spot within the path of totality that day, there are many ways to safely observe the partial solar eclipse here. In California, it starts between 9:01 a.m. (on the Pacific Coast near Point Arena) and 9:11 a.m., when the noon’s penumbral (partial) shadow reaches the far southeast corner of the state, on the Arizona border. The moon’s penumbra begins to withdraw from California just after 11:34 a.m., when the eclipse ends on the Pacific Coast near Capetown. The moon’s outer shadow completely leaves the state just south of the Parker Dam on the Colorado River just after 11:55 a.m.

From most locations in California, the first contact of the moon with the sun’s disk occurs near the top of the solar disk (near “12 o’clock” on the disk, if it is imagined as a clock face). At greatest eclipse, the moon covers the upper left portion of the solar disk, centered near the equivalent of 10 o’clock, leaving a brilliant solar crescent uncovered near 4 o’clock. Last contact of the moon’s disk with the sun will occur at the lower left edge of the disk, near the 8 o’clock position. Of course, you must use proper eye protection to observe these events directly; see the web resources below. If you don’t have a solar filter, you can use projection methods.

Follow the moon before the solar eclipse: On Aug. 7, two weeks before the solar eclipse, there will be a full moon, with a partial lunar eclipse—but that event isn’t visible from our part of the world. (It occurs during our daytime, when the full moon, opposite the sun, is below our horizon.) Instead, watch a nearly full moon rise shortly before sunset of Aug. 6, and just a few minutes after sunset on Aug. 7. For the next several evenings, you can watch the moon rising later each night—or, you can shift your moon viewing time to mornings, either in predawn darkness or in the daytime after sunrise. Observe in the predawn darkness hours on Saturday, Aug. 12, and you’ll catch the Perseid meteor shower nearing its peak. Unfortunately, in 2017 the waning gibbous moon, still over three-quarters full that morning, will brighten the sky and reduce the number of meteors seen.

By the morning of Aug. 15, the moon will be just past last quarter phase, when it’s half full and 90 degrees west of the sun, but by then, the meteor shower activity will be well below peak. On the next morning, Aug. 16, look for bright Aldebaran, eye of Taurus, the Bull, just to the upper right of the crescent moon. Observe beautiful pairings of Venus with the waning crescent moon on Aug. 19 and 20.

As for Perseid meteors in evening: After the full moon of Aug. 7, the moon rises later each night, and by Aug. 11, it rises at 10:14 p.m., more than an hour after the end of evening twilight, at 9:08 p.m. In places far from the bright lights of human settlement—such as in Joshua Tree National Park or Borrego Springs—the sky will be very dark before moonrise, allowing spectacular views of the summer Milky Way and of Perseid meteors. Even before 9 p.m., the sky will be dark enough to observe some meteors. They might be seen anywhere in the sky, and the shower’s “radiant,” or the direction from which the meteors approach Earth, can be found by extending their trails backward to a common origin. Around 9 p.m., the radiant lies just a few degrees above the horizon in the north-northeast. When the radiant is low, the meteoroid particles enter Earth’s atmosphere at a very shallow angle, and very long trails of “Earth-grazing” meteors will be seen. As the night progresses, the radiant in the upper part of the constellation Perseus rises to more than 60 degrees above the horizon by the start of morning twilight, shortly after 4:30 a.m., and our part of the Earth will be presented more broadside to the incoming meteor stream. The meteor count would increase dramatically—were it not for the bright moon after it rises into view.

Good news for 2018: The Perseid peak will occur within two days after new moon, on the night of Aug. 10-11, so it will be a wonderful year for the shower!

Seasonal motions of stars: Venus now dominates the predawn sky, but is getting a little lower each morning, because it is heading toward the far side of the sun, where it will arrive in January 2018.

Annually by the beginning of August, there are several bright stars in the eastern morning sky. During the second week, Procyon and the Dog Star Sirius, the brightest star (not as bright as Venus) rise into view. Beginning then, if you catch Sirius rising in the east-southeast before Altair sets just north of west, you’ll see both the Summer and Winter Triangles—Vega, Altair and Deneb in the west to northwest, and Betelgeuse, Procyon and Sirius in the east to southeast—simultaneously, provided mountains don’t block Altair or Sirius from your view.

Follow the moon in the evening sky after the solar eclipse: Careful viewers might spot the young crescent moon early on Tuesday evening, Aug. 22, just 2 or 3 degrees above the horizon about 25 minutes after sunset, where no surroundings obstruct the view. It’ll be much easier to spot the crescent starting on Aug. 23. Through Aug. 31, notice the moon passing by two planets: Jupiter (with Spica nearby) on Aug. 24 and 25, and Saturn (with twinkling reddish Antares to its west) on Aug. 29 and 30.

To help you plan evening or morning planet viewing during the coming year (August 2017 to August 2018), refer to Jeffrey Hunt’s two-page graphic summary of the moon and planet setting and rising times relative to times of sunset and sunrise, exact for Palm Springs.

To help you plan evening or morning planet viewing during the coming year (August 2017 to August 2018), refer to Jeffrey Hunt’s two-page graphic summary of the moon and planet setting and rising times relative to times of sunset and sunrise, exact for Palm Springs, under the August AM sky chart below.

Wishing you clear skies!

Solar Eclipse information and Resources

http://www.skyandtelescope.com/total-solar-eclipse-august-2017/

http://www.skyandtelescope.com/observing/stargazers-corner/solar-eclipse-lab-sunny-day/

http://www.eclipsewise.com/solar/SEnews/TSE2017/TSE2017.html

https://eclipse.aas.org/

https://eclipse2017.nasa.gov/

https://www.astrosociety.org/education/2017-solar-eclipse-information-resources/

http://static.nsta.org/extras/solarscience/SolarScienceInsert.pdf

http://eclipsophile.com/total-solar-eclipses/total-solar-eclipse-2017-august-21/

http://aa.usno.navy.mil/data/docs/Eclipse2017.php

http://www.astronomy.com/great-american-eclipse-2017

https://www.greatamericaneclipse.com/

Robert C. Victor was a staff astronomer at Abrams Planetarium at Michigan State University. He is now retired and enjoys providing sky watching opportunities for school children in and around Palm Springs. Robert D. Miller did graduate work in planetarium science and later astronomy and computer science at Michigan State University and remains active in research and public outreach in astronomy. Dr. Jeffrey L. Hunt, a retired planetarium director now living in the Chicago area, has taught astronomy and sky watching to all ages.  He studied astronomy education at Abrams Planetarium at Michigan State University. Jeff writes an astronomy blog at jeffreylhunt.wordpress.com and can be followed on Twitter at @jeff_hunt.

Leave a comment

Make sure you enter all the required information, indicated by an asterisk (*). HTML code is not allowed.