The Night Sky This Month: May 2020

night sky stars
Image Credit: Johannes Plenio

Northern hemisphere observers will be able to spot the comet PanSTARRS (C/2017 T2) as it moves through the constellation Ursa Major towards the end of May. The image above shows the comet’s predicted track as it moves past M81 and M82, both of which are two major galaxies in the constellation. Note though that since the comet is north circumpolar, it will not be visible for observers in mid to lower southern latitudes.

Prominent constellations at this time of the year include Gemini, which now sets towards the southwest, Leo with its brightest star Regulus, and Cancer with the Beehive Cluster at its heart. Less conspicuous is Canis Major below Gemini and Virgo in the direction of the great Virgo Cluster of galaxies, which has our Local Group of galaxies as an outlying member.

As always, the north circumpolar constellation Ursa Major is also visible and provided seeing conditions allow, modest amateur equipment will reveal many of its treasures.

Moon Phases In May 2020

Full Moon
Third Quarter
New Moon
First Quarter
May 7th May 14th May 22nd May 30th

Note that the Full Moon on May 7th will be a Super Moon, the last of the four Super Moons for 2020.

The Planets in May 2020

Mercury is now starting to emerge from the Sun’s glare and will become fully visible in the west-northwest by around the 12th of the month when it will have a magnitude of -1.5. Look for Mercury on this date when it will be below Venus. The two planets will also move closer to each other until the 21st, at which time Mercury will be placed about one degree to the lower leftward of Venus. By month’s end, Mercury will have dimmed to magnitude -0.7, but t will gain elevation until the start of July.

Venus still dominates the twilight sky in the south-southwest at the beginning of the month, from an elevation of about 31 degrees. While the planet sets about 3.5 hours at the start of the month, this will reduce to about 30 minutes or so at the end of the month. Note also that the planet’s brightness will dim noticeably from magnitude -4.7 to magnitude -4.2 as its angular diameter decreases from 57 to 40 seconds of arc, and its phase decreases from 24% to only 11%.

Mars is still a pre-dawn object in the southeast, rising as it does at about 03:00 (BST). Now located in the constellation Capricornus, the planet is moving towards Aquarius, which it will reach on the 9th of May. Note that by month’ end, the planet’s magnitude will have increased to 0.0, and its angular diameter to 9.2 seconds of arc, meaning that major surface features of Mars such as Syrtis Major might then be visible in good seeing conditions.

Jupiter rises at about 01:30 (BST) at the beginning of the month shining at magnitude -2.4, but note that while its angular diameter will increase from 41 to 45 seconds of arc, the king of the planets will not rise much above about 12 or so degrees above the south-eastern horizon. The use of an atmospheric dispersion corrector is therefore recommended to obtain reasonable views of the planet.

Saturn rises shortly after Jupiter at the start of May, but by month’s end, it will rise at about midnight (BST). Note that while Saturn’s brightness will increase marginally from +0.6 to +0.4, because of its angular diameter increasing from 17 to 17.8 seconds of arc, the planet will remain below 15 degrees above the horizon. This will make it difficult to obtain clear views of the ring system, which is now tilted towards our line of sight by 21 degrees.

Meteor Showers in May 2020

The Eta Aquarids meteor shower is expected to peak on the night of the 4th/ 5th of May, and although the shower is generally productive, it is best viewed from the southern hemisphere. Nonetheless, while northern observers can expect to see about 30 or so meteors/hour at the peak, bright moonlight on the peak date(s) means that only the brightest meteors will be visible. Although the shower’s radiant is in the constellation Aquarius, meteors can appear from any point in the sky.

Deep Sky Objects to Look For In May 2020

Below are some details of easy targets for modest amateur astronomical equipment in Ursa Major and other prominent constellations.

Bode’s Galaxy – Messier 81 (M81, NGC 3031)

Bode’s Galaxy
Image credit: NASA, ESA

Located about 12 million light-years away in the constellation Ursa Major, M81 is the largest galaxy in the M81 Group, one of several discrete groups of galaxies in the constellation. Although not much detail and structure is shown in this image, the Hubble Space Telescope has resolved not only large star-forming regions in the galaxy but also many massive globular star clusters and even individual stars.

Also not shown here is evidence of the ongoing interaction between M81 and two neighboring galaxies, M82, and NGC 3077. This encounter has resulted in vast amounts of hydrogen gas being stripped from all three galaxies, thus creating large filamentary structures between the galaxies. However, much of the stripped-out gas is now falling back into M82 and NGC 3077, thus causing high rates of star formation in both galaxies.

Messier 49 (M49, NGC 4472)

Located about 56 million light-years away in the constellation Virgo, M49 is the most luminous galaxy in the Virgo Cluster, having an apparent magnitude of 9.4. The most remarkable aspect of M49 is that it contains at least 5,900 massive globular star clusters, all of which are about 10 billion years old, whereas the Milky Way galaxy has fewer than 200 globular clusters.

Perhaps more remarkable is that M49 is thought to contain a supermassive black hole at its core that is estimated to be 565 million times as massive as the Sun. Look for M49 about 4 degrees to the west-south-westward of the bright star Epsilon Virginis.

NGC 2371-2

NGC 2371-2
Image credit:

Located only about 4,400 light-years away in the constellation Gemini, this pretty planetary nebula is listed in the Royal Astronomical Society of Canada’s Finest NGC Objects List, which is a list of easy targets for amateur observers. Look for the nebula a short distance to the southwestward of the bright star Castor.

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