Night sky guide for May 2016

Night sky guide for May 2016

May hosts an above average meteor shower - the Eta Aquarids - with its peak on the night of May 5 and the morning of May 6. This will also be the best time of the month to observe faint objects in the night sky because there is no moonlight to interfere.

A rare transit of Mercury across the Sun will take place on May 9. This is an extremely rare event that occurs only once every few years. There will be one other transit of Mercury in 2019 and then the next one will not take place until 2039. This transit will be visible throughout North America, Mexico, Central America, South America, and parts of Europe, Asia, and Africa.

The second meteor shower of the month - the Alpha Scorpiid meteor shower - will reach its maximum rate of activity on May 13. However, the Moon will be 7 days old at the time, and will present significant interference in the early evening sky.

On May 14 - astronomy and stargazing clubs and other organizations will open their doors to the general public and various astronomy enthusiasts, groups and professionals. Contact your local astronomy club or planetarium to find out about special events they may hold on that day.

The Moon will reach full phase at 21:15 UTC on May 21. This full moon will also be a blue moon, the third of four full moons to fall within one of the Earth's seasons.

  • May 6 - New Moon - 19:29 UTC. The Moon will be located on the same side of the Earth as the Sun and will not be visible in the night sky. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

  • May 5/6 - Eta Aquarid meteor shower. The Eta Aquarid meteor shower will reach its maximum rate of activity on the night of May 5 and the morning of May 6. This is an above average shower, capable of producing up to 60 meteors per hour at its peak, with most of the activity seen in the southern hemisphere. The Moon will be 29 days old at the time of peak activity, and so will present minimum interference. In the northern hemisphere, the rate can reach about 30 meteors per hour. Eta Aquarids are produced by dust particles left behind by comet Halley, known and observed since ancient times. The shower runs annually from April 19 to May 28. The best place to look to see as many meteors as possible is not at the radiant itself, but at any dark patch of sky which is around 90° away from it, since it is at a distance of around 90° from the radiant that meteors will typically appear at their brightest.

  • May 9 - Rare transit of Mercury across the Sun - starting ~11:12 UTC and lasting about 7.5 hours. The planet Mercury will move directly between the Earth and the Sun on May 9, 2016. Viewers with telescopes and approved solar filters will be able to observe the dark disk of the planet Mercury moving across the face of the Sun. This is an extremely rare event that occurs only once every few years. There will be one other transit of Mercury in 2019 and then the next one will not take place until 2039. This transit will be visible throughout North America, Mexico, Central America, South America, and parts of Europe, Asia, and Africa. The best place to view this event in its entirety will be the eastern United States and eastern South America. (Transit Visibility Map and Information)

  • May 9 - Mercury at inferior solar conjunction. From our vantage point on the Earth, Mercury will appear very close to the Sun in the sky as it passes between the Sun and Earth. At closest approach, Mercury and the Sun will appear at a separation of only 0°05', making Mercury totally unobservable for several weeks while it is lost in the Sun's glare. Mercury will also pass perigee – the time when it is closest to the Earth – within a few days of the same time, since it will lie on exactly the same side of the Sun as the Earth in the Solar System. It will move to within a distance of 0.56 AU from the Earth, making it appear with its largest angular size. If it could be observed, it would measure 12.1 arcsec in diameter, whilst appearing completely unilluminated. Mercury's reaching inferior conjunction marks the end of its apparition in the evening sky and its transition to becoming a morning object over the next few weeks.

  • May 11 - M5 well placed for observation. The globular cluster M5 (NGC 5904) in Serpens will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +02°04', it is visible across much of the world; it can be seen at latitudes between 72°N and 67°S. At magnitude 5.8, M5 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

  • May 13 - Alpha Scorpiid meteor shower. Some shooting stars associated with the Alpha Scorpiid meteor shower will be visible from April 20 to May 19, but the shower will reach its maximum rate of activity on May 13. The maximum rate of meteors expected to be visible from a dark location is around 5 per hour. The Moon will be 7 days old at the time of peak activity, and so will present significant interference in the early evening sky. The radiant of the Alpha Scorpiid meteor shower is at around right ascension 16h20m, declination -24°.

  • May 14 - 77P/Longmore at perihelion. Comet 77P/Longmore will make its closest approach to the Sun, at a distance of 2.34 AU.

  • May 14 - International Astronomy Day. Astronomy Day is an annual event intended to provide a means of interaction between the general public and various astronomy enthusiasts, groups and professionals. The theme of Astronomy Day is "Bringing Astronomy to the People," and on this day astronomy and stargazing clubs and other organizations around the world will plan special events. You can find out about special local events by contacting your local astronomy club or planetarium. You can also find more about Astronomy Day by checking the Web site for the Astronomical League.

  • May 15 - Conjunction between the Moon and Jupiter - 08:23 UTC. The Moon and Jupiter will make a close approach, passing within 1°54' of each other. At the moment of closest approach, the Moon will be at mag -12.1, and Jupiter at mag -2.2, both in the constellation LeoThe pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

  • May 21 - Full Moon, Blue Moon - 21:15 UTC. This full moon will also be a blue moon, the third of four full moons to fall within one of the Earth's seasons – defined astronomically to start and end on the Earth's solstices and equinoxes. Normally, only three full moons occur in each of the Earth's four seasons each year. However, there are on average 3.11 full moons within each season. This is because full moons occur on average once every 29.53 days which is slightly less than a third of the length of one of the Earth's seasons – a quarter of the year. As a result, blue moons occur on average once every 2.7 years. This full moon was known by early Native American tribes as the Full Flower Moon because this was the time of year when spring flowers appeared in abundance. This moon has also been known as the Full Corn Planting Moon and the Milk Moon. Over the nights following May 21, the Moon will rise a little under an hour later each day so as to become prominent later in the night. Within a few days, it will only be visible in the pre-dawn and early-morning sky. By the time it reaches last quarter, around a week after full moon, it will rise at around midnight and set at around noon. On this occasion the Moon will lie at a declination of -15°40' in the constellation Libra, and so will appear highest in the southern hemisphere. It will be visible from all latitudes north of 64°N. Its distance from the Earth will be 402 000 km (241 790 miles).

  • May 22 - Mars at opposition - 11:10 UTC. Mars will be well placed for observation, in the constellation Scorpius. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time. Over the weeks following its opposition, Mars will reach its highest point in the sky four minutes earlier each night, gradually receding from the pre-dawn morning sky while remaining visible in the evening sky for a few months. A chart of the path of Mars across the sky in 2016 can be found here, and a chart of its rising and setting times here.

  • May 22 - Conjunction between the Moon and Saturn - 22:18 UTC. The Moon and Saturn will make a close approach, passing within 3°11' of each other. At the moment of closest approach, the Moon will be at mag -12.5, and Saturn at mag 0.8, both in the constellation Ophiuchus. The pair will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.

  • May 27 - M4 well placed for observation. Across much of the world the globular cluster M4 (NGC 6121) in Scorpius will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -26°31', it is easiest to see from the southern hemisphere and cannot be seen from latitudes much north of 43°N. At magnitude 5.9, M4 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

  • May 27 - C/2011 KP36 (Spacewatch) at perihelion. Comet C/2011 KP36 (Spacewatch) will make its closest approach to the Sun, at a distance of 4.88 AU.

Video courtesy Hubble Space Telescope

Sources: InTheSky (Dominic Ford)SeaSky

Featured image background Solar System Scope. Edit: TW

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