The Night Sky This Month: June 2021

Night Sky 5
Image Credit: Felix Mittermeier

The June Solstice occurs at 03:21 (UTC) on the 21st of this month. This date marks the first day of summer in the northern hemisphere and the first day of winter in the southern hemisphere.

Meanwhile, located about 15,000 light years away in the constellation Sagitta (The Arrow), the aptly named, 5,000-year-old  Necklace Nebula is one of only a few known planetary nebulae that did not result from the explosion of a star.

In this case, the nebula resulted from the interaction between two stars in the nebula’s center. The two stars have an orbital period of only 1.2 days, and since the two stars are separated by only about 5 solar radii, the severe gravitational interaction is stripping material from both stars. This material is then ejected from the stars’ combined orbit to form this strikingly beautiful necklace pattern around the stars as they orbit each other.

The Moon Phases in June 2021

Third Quarter
New Moon
First Quarter
Full Moon
June 2nd June 10th June 18th June 24th

Note that the Full Moon occurring on the 24th of the month will be a Super Moon. It will also be the last Super Moon to occur during 2021.

June 10th sees a partial solar eclipse, also known as an annular eclipse, which happens when the Moon’s disc is not quite big enough to cover the entire solar disc as seen from Earth. Observers in Canada, Greenland, and most of Siberia will see a total eclipse, while observers in the UK will only be able to view a partial eclipse.

Provided conditions allow, observers in the UK will see more of the eclipse the further north and west they are located. Here are some examples of how much of the eclipse UK-based observers can expect to see-

  • London – 20%
  • Newcastle – 28%
  • Belfast – 30%
  • Edinburgh – 31%
  • Inverness – 35%

Note that even though UK-based observers will see less than 40% of the eclipse, it is still necessary to view the eclipse only with approved viewing spectacles or other equipment to avoid eye damage.

The Planets in June 2021

Mercury will likely only be visible very low on the northwestern horizon for the first two days of June. Observers that are up for the challenge should note that the little planet sets only a few minutes after the Sun, which could make spotting it very difficult.

Venus starts the month of June with an angular diameter of about 10 seconds of arc and a magnitude of -3.58. However, despite its brightness, the planet will remain at, or below 13 degrees above the northwestern horizon after sunset. The planet is now approaching its point of greatest eastern elongation from the Sun, which it will reach on October 29th. As a result, the planet will steadily increase its elevation until it reaches its highest elevation at the start of December.

Mars begins the month shining at magnitude +1.74 in Gemini, as it moves towards Cancer, which it will reach on the 8th of June. Look for the Red planet about 20 degrees above the north-western horizon soon after sunset. However, Mars will only be visible until August since it will pass behind the Sun in October.

Jupiter begins the month rising at about 01:49 (BST), shining at magnitude -2.43. By month’s end, the ‘King of the Planets’ will rise at about midnight, and although its angular diameter will have increased to 45.14 seconds of arc, it will remain at or below about 22 degrees above the southeastern horizon throughout the month. As a result, it may be difficult to obtain clear views of the planet without the aid of an atmospheric dispersion corrector.

Saturn follows Jupiter’s rising and setting times to within about 20 minutes, and like Jupiter, it will remain within about 20 degrees above the southwestern horizon. As a result, it will be as difficult to get clear views of Saturn, as it will be to get clear views of Jupiter.

Meteor Showers in June 2021

No significant meteor activity is expected to occur during June 2021.

Deep Sky Objects to Look For In June 2021

Prominent constellations at this time of the year include Ursa Major, Ophiuchus, Sagittarius, and Scorpio. However, most prominent of all is Hercules, the 5th largest constellation in the sky. Hercules is home to many spectacular deep shy objects, many of which are perennial favorites of amateur observers the world over. Below are some details of a few objects in this huge constellation-

The Great Globular Cluster – Messier 13 (M13, NGC 6205)

Messier 13
Image credit: NASA

Also known as the Hercules Cluster, this magnitude 5.8 cluster is located about 22,200 light years away from us.

All told, the cluster contains about 300,000 stars that span a distance of 22 minutes of arc, which corresponds to an actual diameter of  145 light years. Although M13 is an easy target for small telescopes and large binoculars, it can generally not be seen without optical aid even in perfect seeing conditions.

Of particular interest is the fact that in 1974, astronomers sent a radio message towards the cluster, to inform potential civilizations there that we exist. However, by the time the message arrives at M13’s current location, the cluster will have moved so far the transmission will miss its target by many light years.

Messier 92 (M92, NGC 6341)

Messier 92
Image credit: NASA

Locate about 27,000 light years away, M92 is not among the brightest of the Milky Way’s globular clusters; it is with an estimated age of 14.2 billion years, also the oldest by a wide margin.

Although its magnitude of 6.3 makes M92 one of the brightest clusters in the Milky Way, it is often overlooked in favor of M13, which is about 20% closer to us, but not far off from our sightline to M13. Thus, if you spot a bright globular cluster in Hercules without optical aid, you are seeing M92, as opposed to M13, which is very difficult to spot with the naked eye.

Hercules A

Hercules A
Image credit: NASA, ESA, S. Baum and C. O’Dea (RIT), R. Perley, and W. Cotton (NRAO, AUI, NSF), and the Hubble Heritage Team (STScI, AURA)

Located about 2,100 million light years from us, Hercules A is an active galaxy that forms a part of the Hercules Cluster of Galaxies. While large amateur telescopes show a faint, fuzzy patch of light, the galaxy’s true nature becomes known when optical images are overlaid with radio images, such as in this composite image.

The areas rendered in pinkish-red here are enormous plasma jets emerging from the galaxy’s core, which houses a black hole that is at least 1,000 times more massive than the black hole in the core of the Milky Way. To balance things out, Hercules A is also at least 1,000 times as massive as the Milky Way, which goes some way towards explaining the 1-million light year reach of the plasma jets.

Note though that 14-inch and larger telescopes are required to spot Hercules A, and even then, you might only see a faint patch of light. Nonetheless, you can keep the image of the plasma jets in mind when you do find Hercules A, which helps to put the sheer size of this elliptical galaxy into some kind of perspective.

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