Night sky guide for April 2018

Night sky guide for April 2018

Three meteor showers will mark April 2018, with Lyrids on April 21 and 22 the most promising one. The first quarter moon will set shortly after midnight, leaving dark skies for the what could be a good show. Best viewing will be from a dark location after midnight. 

The Moon will be located on the same side of the Earth as the Sun and will not be visible in the night sky - New Moon - on April 16. This will be the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.

This month's Full Moon is on April 30.

  • April 1 - Mercury at inferior solar conjunction - 17:47 UTC. Mercury will pass very close to the Sun in the sky as its orbit carries it between the Sun and Earth. This occurs once in every synodic cycle of the planet (116 days) and marks the end of Mercury's apparition in the evening sky and its transition to become a morning object over the next few weeks. At closest approach, Mercury will appear at a separation of only 2°50' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare.

  • April 3 - Conjunction of the Moon and Jupiter - 14:14 UTC. The Moon and Jupiter will share the same right ascension, with the Moon passing 3°53' to the north of Jupiter. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be 17 days old.

  • April 3 - Close approach of the Moon and Jupiter - 16:13 UTC. The Moon and Jupiter will make a close approach, passing within 3°45' of each other. The Moon will be at mag -12.5, and Jupiter at mag -2.4, both in the constellation Libra. 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.

  • April 4 - M94 well placed for observation. M94, a spiral galaxy in Canes Venatici will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of +41°07', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 28°S. At magnitude 8.2, M94 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

  • April 5 - NGC 4755 well placed for observation. Across much of the world, the jewel box open star cluster (NGC 4755, also known as the Kappa Crucis cluster) in Crux will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -60°21', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 9°N. At magnitude 4.2, NGC4755 is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

  • April 7 - Conjunction of the Moon and Saturn - 12:35 UTC. The Moon and Saturn will share the same right ascension, with the Moon passing 1°55' to the north of Saturn. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -11.9, and Saturn at mag 0.2, both in the constellation Sagittarius. 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.

  • April 7 - Close approach of the Moon and Saturn - 12:37 UTC. The Moon and Saturn will make a close approach, passing within 1°55' of each other. The Moon will be at mag -11.9, and Saturn at mag 0.2, both in the constellation Sagittarius. 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.

  • April 7 - Close approach of the Moon and Mars - 18:13 UTC. The Moon and Mars will make a close approach, passing within 3°07' of each other. The Moon will be at mag -11.9, and Mars at mag 0.1, both in the constellation Sagittarius. 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. At around the same time, the two objects will also share the same right ascension – called a conjunction. The Moon will be 21 days old. 

  • April 7 - Conjunction of the Moon and Mars - 18:17 UTC. The Moon and Mars will share the same right ascension, with the Moon passing 3°07' to the north of Mars. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -11.9, and Mars at mag 0.1, both in the constellation Sagittarius. 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.

  • April 12 - Virginid meteor shower. The Virginid meteor shower will reach its maximum rate of activity on April 12, 2018, but some shooting stars associated with the shower are expected to be visible each night from April 7 to 18. Annual meteor showers arise when the Earth passes through streams of debris left behind by comets and asteroids. As pebble-sized pieces of debris collide with the Earth, they burn up at an altitude of around 70 to 100 km, appearing as shooting stars. By determining the speed and direction at which the meteors impact the Earth, it is possible to work out the path of the stream through the Solar System and identify the body responsible for creating it. To date, however, the parent body responsible for creating the Virginid shower has not been identified. The maximum rate of meteors expected to be visible is around 5 per hour (ZHR). However, this assumes a perfectly dark sky and that the radiant of the meteor shower is directly overhead. In practice, the number of meteors you are likely to see is lower than this.

  • April 13 - Omega Cen well placed for observation. Across much of the world the brightest globular cluster in the sky, Omega Centauri will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -47°28', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 22°N. At magnitude 3.7, Omega-Cen is tricky to make out with the naked eye except from a dark site but is visible through a pair of binoculars or a small telescope.

  • April 14 - Haumea at opposition - 17:58 UTC. Haumea will be well placed for observation, in the constellation Bootes. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time.

  • April 16 - New Moon - 01:58 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.

  • April 17 - Conjunction of the Moon and Venus - 19:29 UTC. The Moon and Venus will share the same right ascension, with the Moon passing 5°24' to the south of Venus. The Moon, one day old, will be at mag -9.2, and Venus at mag -3.9, both in the constellation Aries. The pair will be too widely separated to fit within the field of view of a telescope or pair of binoculars but will be visible to the naked eye.

  • April 21, 22 - Lyrids Meteor Shower. The Lyrids is an average shower, usually producing about 20 meteors per hour at its peak. It is produced by dust particles left behind by comet C/1861 G1 Thatcher, which was discovered in 1861. The shower runs annually from April 16 - 25. It peaks this year on the night of the night of the 21st and morning of the 22nd. These meteors can sometimes produce bright dust trails that last for several seconds. The first quarter moon will set shortly after midnight, leaving dark skies for the what could be a good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Lyra but can appear anywhere in the sky.

  • April 22 - M101 well placed for observation. The Pinwheel galaxy (M101, NGC 5457) will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At magnitude 7.9, M101 is quite faint, and certainly not visible to the naked eye, but can be viewed through a pair of binoculars or a small telescope.

  • April 26 - Conjunction of Mars and Pluto - 23:47 UTC. Mars and Pluto will share the same right ascension, with Mars passing 1°25' to the south of Pluto. Mars will be at mag -0.3, and Pluto at mag 14.7, both in the constellation Sagittarius. The pair will be too widely separated to fit within the field of view of a telescope but will be visible through a pair of binoculars.

  • April 28 - α–Scorpiid meteor shower. The α–Scorpiid meteor shower will reach its maximum rate of activity on April 28, 2018. Some shooting stars associated with the shower are expected to be visible each night from April 20 to May 19. The maximum rate of meteors expected to be visible is around 5 per hour (ZHR). However, this assumes a perfectly dark sky and that the radiant of the meteor shower is directly overhead. In practice, the number of meteors you are likely to see is lower than this.

  • April 29 - Mercury at greatest elongation west. The planet Mercury reaches greatest western elongation of 27 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.

  • April 30 - Full Moon - 01:00 UTC. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This full moon was known by early Native American tribes as the Full Pink Moon because it marked the appearance of the moss pink, or wild ground phlox, which is one of the first spring flowers. This moon has also been known as the Sprouting Grass Moon, the Growing Moon, and the Egg Moon. Many coastal tribes called it the Full Fish Moon because this was the time that the shad swam upstream to spawn.

  • April 30 - Conjunction of the Moon and Jupiter - 17:16 UTC. The Moon and Jupiter will share the same right ascension, with the Moon passing 3°49' to the north of Jupiter.  At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.6, and Jupiter at mag -2.5, both in the constellation Libra. 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. The Moon will be 14 days old.

  • April 30 - Close approach of the Moon and Jupiter - 19:17 UTC. The Moon and Jupiter will make a close approach, passing within 3°40' of each other. The Moon, 14 days old, will be at mag -12.6, and Jupiter at mag -2.5, both in the constellation Libra. 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. At around the same time, the two objects will also share the same right ascension – called a conjunction.

Video courtesy Hubble Space Telescope

Sources In The Sky by Dominic Ford, NASA, The Watchers

Featured image: Lyrids meteor shower stream. Credit: MeteorShowers.org. Edit: TW

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