See what's up in the night sky for April 2020, including stargazing events and the moon's phases, in this Space.com gallery courtesy of Starry Night Software.
Wednesday, April 1 at 10:21 GMT—First Quarter Moon
The moon will reach its first quarter phase on Wednesday, April 1 at 10:21 GMT. At that time, the relative positions of the Earth, sun, and moon will cause us to see the moon half illuminated—on the western (right-hand) side. Sunlight striking the moon at a shallow angle produces spectacularly illuminated landscapes along the pole-to-pole terminator that separates the lit and dark hemispheres. First quarter moons rise at noon and set at midnight, so they are visible starting in the afternoon hours. The term "first quarter" refers not to the moon's appearance, but the fact that our natural satellite has now completed the one quarter of its orbit around Earth, counting from the last new moon.
Thursday, April 2 all night—Juno at Opposition
On Thursday, April 2, the major main belt asteroid Juno will reach opposition. At that time, Earth will be passing between the asteroid and the sun, minimizing our distance from Juno and causing it to appear at its brightest and largest for this year. The magnitude 9.5 object will be visible in backyard telescopes all night long. On opposition night, Juno will be positioned below the star Delta Virginis, aka Auva, which marks the northwestern corner of Virgo's body. One week later, Juno's motion northward across the foreground stars (red path with labeled date:time) will bring it within 0.5 degrees of that star, allowing both objects to appear together in telescopes for several nights.
Friday, April 3 between midnight and dawn—Moon Buzzes the Beehive Cluster
In the western sky between midnight and dawn on Friday, April 3, the waxing gibbous moon will be positioned less than three finger widths to the lower right (or 2.5 degrees to the celestial west) of the large open star cluster known as the Beehive or Messier 44 in the constellation of Cancer, the Crab. Observers in western North America will see the moon pass just north of the centre of the cluster. The moon passes through, or close to, this cluster frequently because the Beehive is located only 1 degree north of the ecliptic (green line). To better see the cluster's stars, try placing the bright moon just outside the field of view of your binoculars (red circle).
Friday, April 3 evening—Venus Crosses the Pleiades
In the western sky on the evening of Friday, April 3, Venus' orbital motion (red path with date:time labels) will carry it through the bright Pleiades Star Cluster, otherwise known as Messier 45, the Seven Sisters, the Hole in the Sky, and Subaru. Venus passes that cluster every year—but the orbital mechanics of Earth and Venus only produce traverses of the cluster in a dark sky every eight years, making this event a celestial highlight for 2020. Venus and the cluster will fit together in the field of view of binoculars for several nights surrounding the 3rd, and within the narrower field of backyard telescopes (red circle) from April 2 to 4.
Saturday, April 4 evening—Sirius Sparkles in the Southwest
After dusk in early April annually, the night sky's brightest star, Sirius, or Alpha Canis Majoris, sparkles in the lower part of the southwestern sky. Sirius is a hot, white, A-class star located only 8.6 light-years from Earth — part of the reason for its bright appearance. For mid-northern latitude observers, Sirius is always seen in the lower third of the sky, through a thicker blanket of Earth's refracting atmosphere. This produces the strong twinkling and flashes of color the Dog Star is known for.
Tuesday, April 7 all night—The Apollo Landing Sites
The six crewed Apollo Missions were sent to different regions of the moon in order to carry out experiments and to bring back rock samples that help us determine the age and composition of the moon's surface. For safety reasons, Apollo 11 was sent to the flat and relatively featureless terrain of Mare Tranquillitatis "Sea of Tranquility" near the moon's equator (red line). Later missions landed in more rugged regions with complex geology. When the moon approaches the full phase, all of the regions where the astronauts explored are illuminated by sunlight, but no telescope on Earth is strong enough to see the equipment left on the moon.
Wednesday, April 8 at 2:35 GMT—Full Pink Moon
The moon will reach its full phase at 2:35 GMT on Wednesday, April, 8. That corresponds to 10:35 p.m. EDT on Tuesday, April 7. April's full moon, known as the Pink Moon, Sprouting Grass Moon, Egg Moon, or Fish Moon, always shines in or near the stars of Virgo. Full moons always rise in the east as the sun sets, and set in the west at sunrise. When fully illuminated, the moon's geology is enhanced—especially the contrast between the bright, ancient, cratered highlands and the darker, younger, smoother maria. This full moon will occur less than 9 hours after perigee, the point in the moon's orbit when it is closest to Earth, generating high tides worldwide and making this the second of three consecutive supermoons in 2020.
Friday, April 10 all night—The Little Dipper Points Sideways
Polaris marks the tip of the handle of the Little Dipper, the asterism we also know as the constellation Ursa Minor, the Little Bear. In mid-April after dusk, the rest of the Little Dipper extends sideways to the right from Polaris, and curves strongly upwards towards the Big Dipper. The two dippers flank the tail stars of Draco the Dragon. The magnitude 2.06 star at the outer edge of the Little Dipper's bowl (and closest to the Big Dipper) is slightly dimmer than Polaris. This medium-cool, reddish star is named Kochab. The other five stars of the dupper may be too dim to see from the city, but binoculars will reveal them.
Tuesday, April 14 at 22:56 GMT—Last Quarter Moon
The moon will reach its last quarter phase at 22:56 GMT on Tuesday, April 14. At last quarter, the moon rises around midnight and remains visible in the southern sky during morning daylight. Last quarter moons are illuminated on the eastern side, towards the pre-dawn sun. At that time of its orbit, the moon is also positioned ahead of the Earth in our trip around the sun. About 3½ hours later, earth will occupy that same location in space. After this phase, the waning moon will traverse the final quarter of its orbit around the earth, on the way to new moon.
Tuesday, April 14 pre-dawn—Waning Moon Approaches Planets
In the southeastern sky during the hours before sunrise, for four mornings starting on Tuesday, April 14, the waning moon's orbital motion from west to east (or right to left as viewed from the Northern Hemisphere) will carry it close past three bright planets—Jupiter, Saturn, and Mars. On Tuesday morning, look for the moon sitting a generous palm's width to the right (or 7 degrees to the celestial west) of bright, white Jupiter — with yellowish Saturn and reddish Mars arrayed to their left. The scene will make a fine wide field photograph when composed with some interesting landscape scenery.
Wednesday, April 15 pre-dawn—The Moon Meets Saturn
The old moon's trip past the planets will continue on Wednesday, April 15—in the southeastern sky in the hours before sunrise. After 24 hours of travel eastward, the moon will now sit a few finger widths directly below (or 3 degrees to the celestial south of) yellowish Saturn, with brighter Jupiter positioned to their upper right (west) and reddish Mars off to their left (east). The arrangement will offer another lovely photo opportunity.
Thursday, April 16 pre-dawn—Crescent Moon Near Mars
Visible in the southeastern sky on Thursday morning between 5 a.m. local time and sunrise, the crescent moon will jump east to take up a position four finger widths to the lower left (or 3.5 degrees to the celestial southeast) of reddish Mars. Yellowish Saturn and bright, white Jupiter will be positioned a generous fist's diameter to the upper right of Mars. This will be the third of four consecutive mornings that will offer a fine photo opportunity featuring the moon and bright planets.
Friday, April 17 pre-dawn—Crescent Moon East of Three Planets
This month's visit of the bright planets by the moon concludes on Friday, April 17 with the crescent moon positioned 1.3 fist diameters to the lower left (or 13 degrees to the celestial east) of Mars, Saturn, and Jupiter in the southeastern sky before sunrise. The three planets, plus the yet-to-rise sun, will nicely define the plane of our solar system across the sky (green line); although the moon's 5 degree orbital inclination allows it to stray by up to that distance from that plane — in this case, below it. The moon will be close enough to the planets to warrant yet another wide-field photograph. If you capture the moon's trip on all four consecutive mornings, send your photos to Space.com!
Saturday, April 18 all night—Comet Atlas in the Northern Sky
A comet designated c/2019 Y4 (ATLAS) is predicted to become bright enough to see with unaided eyes in May. If this holds true, and comets are notoriously unpredictable, the comet should be observable in binoculars during April, too. The moonless nights surrounding the weekend of Saturday, April 18 are the best in April month for finding it. Once the sky has darkened, face northwest, and sweep your binoculars inside the large triangle formed by the bright star Capella, dimmer Polaris, and the Big Dipper. The comet's path during April (red line with date:time labels) will be downwards between Capella and Polaris. In binoculars, the comet should appear as faint, fuzzy grey patch, and elongated due to a developed tail (simulated view inset). Once you've located it, a backyard telescope might also show a hint of green, a characteristic color of these icy visitors.
Sunday, April 19 all night—Ursa Major Galaxies
The Big Dipper is part of a larger constellation, namely Ursa Major, the Big Bear. As a circumpolar constellation, it moves to a location very high in the northern sky in late evening during mid-April –ideal for observing the many galaxy showpieces within it. They can be seen through strong binoculars or backyard telescopes on the dark nights surrounding this weekend. Drawing a line connecting the stars Phecda to Dubhe, and extending it by an amount equal to their separation, brings one to Bode's Nebula, otherwise known as the galaxies Messiers 81 and 82. M81 is a magnitude 6.9 spiral galaxy oriented not quite face-on to Earth, making it larger and brighter than M82. M82, located half of a degree to the north of M81, is smaller, but bright due its nearly edge-on orientation. Several other dimmer galaxies can be found within a few degrees of Bode's Nebula.
Wednesday, April 22 pre-dawn—Lyrids Meteor Shower Peak
The annual Lyrids meteor shower, derived from particles dropped by comet C/1861 G1 (Thatcher), runs from April 16 to 28, and will peak in intensity around 18:00 GMT on Wednesday, April 22. The best viewing time will be between midnight and dawn on Wednesday, with fewer meteors on the mornings before and after. The meteors will streak away from a point in the sky (the shower's radiant) near the bright star Vega, which will be high in the eastern sky before dawn. The Lyrids can produce up to 18 meteors per hour, with occasional fireballs. A nearly new moon will leave the skies nice and dark for this year's shower.
Thursday, April 23 at 2:26 GMT—New Moon
At its new phase on Thursday, April 23 at 2:26 GMT, the moon will be travelling between the Earth and the sun. Since sunlight is only shining on the side of the moon aimed away from us, and the moon is in the same region of the sky as the sun, the moon is hidden from view everywhere on Earth for about a day.
Friday, April 24 all night—Whirlpool and Pinwheel Galaxies
On evenings during April, the Big Dipper is high in the northeastern sky. The bright star Alkaid marks the bottom tip of the dipper's handle. Two impressive galaxies can be seen near that star in binoculars (red circle) and backyard telescopes under dark sky conditions. The Pinwheel Galaxy, a spectacular, large face-on spiral galaxy also designated as Messier 101 sits a palm's width to the left (or 5.5 degrees to celestial north) of Alkaid, forming an equilateral triangle with Alkaid and Mizar, the double star where the handle bends. This relatively close galaxy (21 million light-years away) is nearly as large as the full moon in the sky—but with the galaxy's light spread over such a large area, its overall brightness is low. If you search the sky 3.5 degrees to the upper right of Alkaid, you will come to the iconic spiral Whirlpool Galaxy, aka Messier 51. This galaxy's angular size is smaller, but it will appear brighter in your binoculars and telescope (inset). M51 has a secondary galaxy core designated NGC5195 right beside it—linked by a bridge of material.
Sunday, April 26 starting at 11:40 GMT—Crescent Moon Covers Vesta
On Sunday, April 26, commencing at about 11:40 GMT, observers in parts of China, Southeast Asia, Philippines, and Southern Japan can see the crescent moon move in front of (or occult) the large main belt asteroid Vesta, as shown here for Taiwan. The event will occur in the western sky after dusk, with the dark leading edge of the moon covering the magnitude 8.5 asteroid first. (Times vary by location — use Starry Night or another app to determine your local circumstances.)
Sunday, April 26 evening—Crescent Moon meets Venus
In the western sky after dusk on Sunday, April 26, the thin, waxing crescent moon will make a pretty sight when it sits a palm's width to the left (or 6 degrees to the celestial south) of Venus. The moon and the planet will make a pretty widefield photograph. On the nights before and after, the moon will also be there—but lower and higher than Venus, respectively.
Monday, April 27 evening—Crescent Moon near Messier 35
In the western sky on the evening of Monday, April 27, the waxing crescent moon will pass close to three medium-bright stars named Tejat, Propus, and 1 Geminorum, which form the feet of Castor, the more westerly twin of Gemini. At the same time, your binoculars might reveal a tight cluster of stars sitting less than 2 finger widths to the right (or 1.75 degrees to the celestial northwest) of the moon. That's an open star cluster known as Messier 35, M35, or more appropriately, the Shoe-Buckle Cluster. The cluster and the moon will be close enough to fit together in the field of view of binoculars (red circle) — but the cluster will be more apparent if you keep the bright moon just outside your binoculars' field of view.
Monday, April 27 evening—Venus at Maximum Brightness
On Monday, April 28, the evening planet Venus will achieve its "greatest illuminated extent" for the current lengthy evening apparition. That terminology describes the optimum combination of the approaching planet's apparent disk size (38 arc-seconds) and its illuminated phase. That evening, Venus will shine at a spectacular magnitude –4.73. Its 27% illuminated crescent phase (inset) will be apparent in any telescope or spotting scope, good binoculars—or even to very sharp, unaided eyes.
Wednesday, April 29 around 9:45 p.m. EDT—Lunar X
Several times a year, for a few hours near its first quarter phase, a feature on the moon called the Lunar X becomes visible in strong binoculars and backyard telescopes. When the rims of the craters Parbach, la Caille, and Blanchinus are illuminated from a particular angle of sunlight, they form a small, but very obvious X-shape. The phenomenon called is pareidolia—the tendency of the human mind to see familiar objects when looking at random patterns. The Lunar X is located near the terminator, about one third of the way up from the southern pole of the Moon (at 2° East, 24° South). The prominent round crater Werner sits to its lower right. On Wednesday, April 29, the Lunar X is predicted to peak in intensity at 9:44 p.m. EDT (or 01:44 GMT on Thursday, April 30)—but the phenomenon will be visible for approximately two hours on either side of that time. This event should be visible wherever the moon is shining in a dark sky during that time window. Simply adjust for your difference from the Eastern Time zone. For the Americas, the Moon will be positioned in the southwestern evening sky.
Thursday, April 30 wee hours—Moon near the Beehive Again
Low in the northwestern sky in the wee hours of Thursday, April 30 to see the waxing half-illuminated moon positioned a palm's width to the lower right (or 6 degrees to the celestial west) of the large open star cluster known as the Beehive or Messier 44 in the constellation of Cancer, the Crab. This is the moon's second such meeting in April. Observers in Asia will see the moon skim past the northern edge of the cluster. The moon passes close to, or through, this cluster frequently because the Beehive is located only 1 degree north of the ecliptic (green line).
Thursday, April 30 at 20:38 GMT—2nd First Quarter Moon of April
When a lunar phase occurs on the first day of a calendar month, it can repeat at month-end — so tonight brings a first quarter phase for the second time this April. When the moon reaches its first quarter phase, the relative positions of the Earth, sun, and moon cause us to see the moon half illuminated—on the western (right-hand) side. Sunlight striking the moon at a shallow angle produces spectacularly illuminated landscapes along the pole-to-pole terminator that separates the lit and dark hemispheres. First quarter moons rise at noon and set at midnight, so they are visible starting in the afternoon hours. The term first quarter refers not to the moon's appearance, but the fact that our natural satellite has now completed one quarter of its orbit around Earth, counting from the last new moon.