Night Sky Guide for April 2019

April 1 – M104 well placed for observation. The Sombrero galaxy (M104, NGC 4594) will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -11°37', it is easiest to see from the southern hemisphere; it can be seen at latitudes between 58°N and 81°S. At magnitude 8.0, M104 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 2 – Conjunction of the Moon and Venus – 04:19 UTC. The Moon and Venus will share the same right ascension, with the Moon passing 2°40' to the south of Venus. The Moon will be 27 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -10.0, and Venus at mag -4.0, both in the constellation Aquarius. 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 2 – Close approach of Moon and Venus – 06:11 UTC. The Moon and Venus will make a close approach, passing within 2°32' of each other. The Moon will be 27 days old. The Moon will be at mag -9.9, and Venus at mag -4.0, both in the constellation Aquarius. 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.

April 2 – Conjunction of Mercury and Neptune – 18:15 UTC. Mercury and Neptune will share the same right ascension, with Mercury passing 0°22' to the north of Neptune. Mercury will be at mag 0.7, and Neptune at mag 8.0, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

April 3 – Conjunction of the Moon and Mercury – 23:03 UTC. The Moon and Mercury will share the same right ascension, with the Moon passing 3°37' to the south of Mercury. The Moon will be 27 days old. The Moon will be at mag -9.4, and Mercury at mag 0.7, both in the constellation Aquarius. 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 – New Moon – 08:52 UTC. The Moon will pass close to the Sun and become lost in the Sun's glare for a few days. The Moon's orbital motion carries it around the Earth once every four weeks, and as a result, its phases cycle from new moon, through first quarter, full moon and last quarter, back to new moon once every 29.5 days. This motion also means that the Moon travels more than 12° across the sky from one night to the next, causing it to rise and set nearly an hour later each day. At new moon, the Earth, Moon and Sun all lie in a roughly straight line, with the Moon in the middle, appearing in front of the Sun's glare. In this configuration, we see almost exactly the opposite half of the Moon to that which is illuminated by the Sun, making it doubly unobservable because the side we see is unilluminated. Over coming days, the Moon will rise and set an hour later each day, becoming visible in the late afternoon and dusk sky as a waxing crescent which sets soon after the Sun. By the first quarter, in a week's time, it will be visible until around midnight.

April 5 – Asteroid 7 Iris at opposition – 14:24 UTC. Asteroid 7 Iris will be well placed for observation, lying in the constellation Corvus, well above the horizon for much of the night. Regardless of your location on the Earth, 7 Iris will reach its highest point in the sky at around midnight local time.

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 6 – Asteroid 2 Pallas at opposition – 16:48 UTC. Asteroid 2 Pallas will be well placed for observation, lying in the constellation Bootes, well above the horizon for much of the night. Regardless of your location on the Earth, 2 Pallas will reach its highest point in the sky at around midnight local time.

April 9 – Conjunction of the Moon and Mars – 06:41 UTC. The Moon and Mars will share the same right ascension, with the Moon passing 4°43' to the south of Mars. The Moon will be 4 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -10.6, and Mars at mag 1.5, both in the constellation Taurus. 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 9 – Close approach of the Moon and Mars – 08:51 UTC. The Moon and Mars will make a close approach, passing within 4°35' of each other. The Moon will be at mag -10.7, and Mars at mag 1.5, both in the constellation Taurus. 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.

April 10 – Conjunction of Venus and Neptune – 03:43 UTC. Venus and Neptune will share the same right ascension, with Venus passing 0°18' to the south of Neptune. Venus will be at mag -3.9, and Neptune at mag 8.0, both in the constellation Aquarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

April 11 – Mercury at greatest elongation east – 15:37 UTC. Mercury will reach its greatest separation from the Sun in its March–April 2019 morning apparition. It will be shining brightly at mag 0.3.

April 12 – Virginid Meteor Shower. The Virginid meteor shower will reach its maximum rate of activity on April 12, 2019, but some shooting stars associated with the shower are expected to be visible each night from April 7 to 18. 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.

April 13 – Mercury at dichotomy – 01:16 UTC. Mercury will reach half phase in its 2019 morning apparition. It will be shining brightly at mag 0.2.

April 13 – 136199 Eris at solar conjunction – 20:47 UTC. 136199 Eris will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth. At closest approach, 136199 Eris will appear at a separation of only 11° from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare. At around the same time, 136199 Eris will also be at its most distant from the Earth – receding to a distance of 97.04 AU – since the two planets will lie on opposite sides of the solar system. If 136199 Eris could be observed at this time, it would appear at its smallest and faintest on account of its large distance. It would measure 0.0 arcsec in diameter.

April 13 – Close approach of the Moon and M44 – 20:47 UTC. The Moon and M44 will make a close approach, passing within 0°04' of each other. The Moon will be at mag -12.2, and M44 at mag 3.1, both in the constellation Cancer. The pair will be close enough to fit within the field of view of a telescope, but will also be visible through a pair of binoculars.

April 13 – NGC 5128 well placed for observation. Across much of the world, Centaurus A (NGC 5128) will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -43°01', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 26°N. At magnitude 7.0, NGC5128 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 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 – M51 well placed for observation. The whirlpool galaxy (M51, NGC 5194) 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°11', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 22°S. At magnitude 8.4, M51 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 16 – 136108 Haumea at opposition – 01:22 UTC. 136108 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 – M83 well placed for observation. Across much of the world the southern pinwheel galaxy (M83, NGC 5236), a face-on spiral galaxy in Hydra will be well placed for observation. It will reach its highest point in the sky at around midnight local time. At a declination of -29°51', it is easiest to see from the southern hemisphere but cannot be seen from latitudes much north of 40°N. At magnitude 7.5, M83 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 17 – M3 well placed for observation. The globular cluster M3 (NGC 5272) 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 +28°22', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 41°S. At magnitude 6.3, M3 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 19 – Full Moon – 11:13 UTC. The Moon will reach full phase. At this time in its monthly cycle of phases, the Moon lies almost directly opposite the Sun in the sky, placing it high above the horizon for much of the night. The sequence of full moons through the year are often assigned names according to the seasons in which they fall. This month's will be the second to fall in spring 2019 – the Milk Moon. Over the nights following April 19, the Moon will rise around an hour later each day, becoming 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, a week after full moon, it will rise at around midnight and set at around noon. At the exact moment when the Moon reaches full phase, it will lie at a declination of -06°25' in the constellation Virgo, and so will appear high in the sky at all but the most extreme latitudes. It will be visible at all latitudes between 73°N and 86°S. Its distance from the Earth will be 368 000 km (228 664 miles).

April 23 – Uranus at solar conjunction -23:09 UTC. Uranus will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth. At closest approach, Uranus will appear at a separation of only 0°29' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare. At around the same time, Uranus will also be at its most distant from the Earth – receding to a distance of 20.85 AU – since the two planets will lie on opposite sides of the solar system. If Uranus could be observed at this time, it would appear at its smallest and faintest on account of its large distance. It would measure 3.4 arcsec in diameter. Over the following weeks and months, Uranus will re-emerge to the west of the Sun, gradually becoming visible for ever-longer periods in the pre-dawn sky. After around six months, it will reach opposition, when it will be visible for virtually the whole night.

April 23 – Lyrid Meteor Shower. The Lyrid meteor shower will reach its maximum rate of activity on April 23, 2019, but some shooting stars associated with the shower are expected to be visible each night from April 19 to 25. The parent body responsible for creating the Lyrid shower is C/1861 G1 (Thatcher). The maximum rate of meteors expected to be visible is around 10 per hour (ZHR). However, this assumes a perfectly dark sky and that the radiant of the meteor shower is directly overhead.

April 23 – Conjunction of the Moon and Jupiter – 11:35 UTC. The Moon and Jupiter will share the same right ascension, with the Moon passing 1°38' to the north of Jupiter. The Moon will be 18 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.4, and Jupiter at mag -2.4, both in the constellation Ophiuchus.

April 23 – Close approach of the Moon and Jupiter – 11:58 UTC. The Moon and Jupiter will make a close approach, passing within 1°37' of each other. The Moon will be at mag -12.4, and Jupiter at mag -2.4, 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.

April 23 – 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 a declination of +54°20', it is easiest to see from the northern hemisphere but cannot be seen from latitudes much south of 15°S. 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 25 – Conjunction of the Moon and Saturn – 14:27 UTC. The Moon and Saturn will share the same right ascension, with the Moon passing 0°22' to the south of Saturn. The Moon will be 20 days old. At around the same time, the two objects will also make a close approach, technically called an appulse. The Moon will be at mag -12.1, and Saturn at mag 0.3, both in the constellation Sagittarius. The pair will be close enough to fit within the field of view of a telescope, but will also be visible to the naked eye or through a pair of binoculars.

April 25 – Close approach of the Moon and Saturn – 13:30 UTC. The Moon and Saturn will make a close approach, passing within 0°22' of each other. The Moon will be at mag -12.1, and Saturn at mag 0.3, both in the constellation Sagittarius. The pair will be close enough to fit within the field of view of a telescope, but will also 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.

April 25 – Close approach of the Moon and Pluto – 19:49 UTC. The Moon and 134340 Pluto will make a close approach, passing within 0°04' of each other. The Moon will be at mag -12.0, and 134340 Pluto at mag 14.7, both in the constellation Sagittarius. The pair will be close enough to fit within the field of view of a telescope, but will also 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, 2019. However, some shooting stars associated with the shower are expected to be visible each night from April 20 to May 19. The parent body responsible for creating the α–Scorpiid shower has been tentatively identified as 2004 BZ74. 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. 

Video courtesy Hubble Space Telescope

Sources: In The Sky by Dominic Ford, NASA, TW

Featured image credit: NASA, TW