The Night Sky This Month: August 2020

Perseids

In the August, the Milky Way can be seen passing through the constellations of Sagittarius, Cygnus, Lyra, Aquila, Cassiopeia and Perseus. Meanwhile, the year’s most reliable meteor shower, the Perseids, is expected to peak on the 11/12th of the month. Turning our attention to the planets, Venus can be seen shinning brightly at dawn, while Jupiter and Saturn continue to dominate the night sky and can be seen low in the south after dark.

The Planets in August 2020

Mercury is now approaching the Sun, and while it is just barely visible in the pre-dawn sky, the little planet will become lost behind the Sun on the 17th of the month.

Venus rises at about 2 AM (BST) in the north-north-east throughout August, but since the Sun rises earlier each day, the interval between when Venus rises and Sunrise increases by about 20 minutes or so each day. Nonetheless, Venus starts the month shining at magnitude -4.5, which will dim somewhat to magnitude -4.3 towards the end of the month as the planet’s angular diameter decreases from 27 seconds of arc to 20 seconds of arc. Note that even though Venus is now approaching its point of maximum western elongation from the Sun, its illumination will increase to 59% from 43%, which explains its near-constant brightness throughout the month.

Venus starts the month in the constellation Taurus, but it will pass into the upper reaches of Orion on the 5th of the month before continuing towards Gemini, which it will reach on the 13th of August. By month’s end, Venus will be visible about 9 or so degrees below the bright star Pollux in Gemini.

Mars is now visible in the southeast as the month starts, shining at magnitude -1.1, which will increase somewhat to magnitude -1.8 towards the month’s end. Since the Red planet’s angular diameter will increase from 14.6 seconds of arc to about 18.7 seconds of arc, it should be easy to spot with small telescopes about 40 degrees above the horizon. Provided that seeing conditions are favorable, it should also be possible to discern some major surface features.

Jupiter remains visible to the upper leftward of the Teapot asterism in Sagittarius throughout the month. Although it remains relatively bright at about magnitude -2.7, the planet will not rise more than about 16 degrees above the southern horizon when it transits meridian. However, with the aid of an atmospheric dispersion corrector, it might be possible to view the Great Red Spot on the dates and (UT) times below-.

  • 1st –    22:23
  • 8th –   23:09
  • 13th –  22:17
  • 18th –  21:25
  • 25th –  22:11
  • 30th –  21:19

Saturn was in opposition on the 20th of July, and it will, therefore, be visible throughout August. Note that Saturn lags behind Jupiter by only about 8 degrees, so the two planets will dominate the night sky throughout the month. However, like Jupiter, Saturn will remain below 16 degrees above the southern horizon throughout August, meaning that an atmospheric dispersion corrector might be required to obtain even reasonable views of the ring system, which now spans across 42 seconds of arc.

The Moon phases in August 2020

Full Moon
Third Quarter
New Moon
First Quarter
August 3rd
August 11th August 19th August 25th

Meteor Showers in August 2020

The Perseids meteor shower is expected to peak on the night of 11/12 August, and although this shower usually produces large, bright meteors at the hourly rate of about 60 or so during the peak, the second quarter Moon will make it difficult to observe many fainter meteors this year. While this shower typically runs from about the 17th of July to about the 24th of August, the best viewing will occur in the pre-dawn hours on the 12th of August.

Deep Sky Objects to Look For In August 2020

This month, prominent constellations include Ursa Major, Hercules, Ophiuchus, Sagittarius, Scorpius, Boötes, Cygnus, and Lyra. Also visible at this time is the arc of stars that make up Corona Borealis, and the bright stars Deneb in Cygnus, Vega in Lyra and Altair in Aquila that constitute the Summer Triangle. While all of these constellations contain many spectacular deep sky objects, one other constellation that is now coming into view is Aquila, which contains several deep-sky objects that are worth hunting down with small to medium telescopes. Below are some details of a few of these objects-

NGC 6760 / NGC 6749

NGC 6760 / NGC 6749
Image credit: Wikisky

This image shows two globular star clusters in the same field of view, with NGC 6760 at the lower left of the frame, and NGC 6749 at the top right corner of the frame. Note the striking color contrast between the two clusters as the result of large differences in the ages and spectral types of the stars that inhabit each cluster. Equally striking is the line of three blue stars that cuts diagonally across the imaginary line that connects the two clusters, but note that while these stars appear blue in this image, a small to medium telescope will show them as very bright white to slightly yellow stars.

The Glowing Eye Nebula – NGC 6751

The Glowing Eye Nebula
Image credit: NASA / The Hubble Heritage Team (STScI/AURA)

This hugely complex planetary nebula is located about 6,500 light-years away and shines with a magnitude of 11.9. The bright spot at the center of the nebula is the remains of the progenitor star, which now has an estimated surface temperature of 140,0000C. While this is neither the biggest, nor the fastest-growing nebula known, it has an apparent diameter of 0.43′, and it is expanding at the rate of about 40 km/second. Look for the nebula about 1.1 degrees southward of the bright star Lambda Aquilae.

NGC 6709

NGC 6709
Image credit: Wikisky

This open star cluster is not particularly big or densely populated. However, the high number of bright, blue stars it contains makes it stand out particularly well against the dense, but dim starfield behind it. Although a small telescope will only reveal the brightest stars,  medium to large instruments will resolve most of the member stars that are loosely arranged in a rough diamond shape. Look for this pretty cluster about 5 degrees to the south-west of the star Zeta Aquilae.

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