April provides a chance to see nearly all the most famous constellations in one night, from Orion to Scorpius. Saturn shines all night, and the Lyrid meteor shower returns.
Saturn night fever: Saturn is the only evening planet in April, but we’ll have it all night long. Saturn shines brighter than most stars and has a distinct yellow color. Throughout April, Saturn appears in the east at sunset; is about two-thirds of the way up in the south in the middle of the night; and sets about dawn.
More specifically: Saturn reaches opposition on the evening of April 3-4. This means that Saturn is on exactly the other side of the Earth from the sun. This also means that in early April, Saturn will rise in the west at sunset, be high overhead at midnight and set at dawn.
In mid-April, Saturn will be about 20 degrees up in the east at dusk (two fists at arm’s length); due south at 11 p.m.; and will set in the west around 5:30 a.m.
In late April, Saturn will be about halfway up the eastern sky at dusk; will be due south at about 10:45 p.m.; and will set in the west about 4:30 a.m.
Look for the bluish star Spica in Virgo below Saturn, which is enclosed in a triangle of bright stars that also includes Regulus in Leo and Arcturus (Hokulea) in Bootes.
The rings are clearly visible with a medium-size telescope. In early April, Saturn will be only 800 million miles from Earth, the closest approach this year.
Look for the almost-full moon next to Saturn on the night of April 16-17.
Venus lights up the morning sky: Venus keeps blazing away in the morning sky, though it’s much lower at dawn than it was earlier this year. Look for the waning crescent moon next to Venus on April 1 and April 30.
Jupiter returns to the morning sky: Jupiter vanished from the evening sky in late March and pops into the morning sky at the very end of April. Look for the planet around April 30, rising in the east around 5:10 a.m. However, you’ll only have about 30 minutes to spot Jupiter before the rising sun washes it out.
Mercury and Mars just barely squeak into the morning sky: Mercury and Mars both return to the morning sky in the last 10 days of April and should be easily visible with binoculars.
Mars shines at first magnitude and is the lower of the two planets. Mercury shines at second magnitude on April 21 but brightens considerably by the end of April. The two planets are within 2 degrees of each other on April 21 and rise together at about 5:20 a.m. As the final days of April unfold, Mars and Mercury appear to draw apart, with Mars joining Jupiter and Mercury rising toward Venus. This leads to a …
Gathering of planets: The view of the pre-dawn sky about 5:15 a.m. on April 30 should be spectacular if you have: 1) a clear morning; 2) an unbroken view of the eastern sky; and 3) a pair of binoculars to spot Mars. On the morning of April 30, the crescent moon will be above Venus; Venus will blaze at minus 4 magnitude; Mercury will shine at 0.95 magnitude just below Venus; Jupiter will shine at minus 2 magnitude down below Venus; and faint Mars will shimmer less than half a degree above Jupiter.
Lyrid Meteor Shower: Stay up late on April 21 and then look for meteors after midnight, very early on April 22. The shower is active April 16-25. While not one of the strongest showers, the Lyrids can produce up to 20 meteors per hour. There will be interference from the waning gibbous moon, which rises at about 11:10 p.m. on April 21 and is in the sky till dawn.
THE APRIL SKY MAP
The map, set for the latitude of Honolulu, is good for 9 p.m. at the start of April and 8 p.m. in the middle of the month.
Over in the west, we have a final chance to see the great constellations of winter before they vanish into the sun. The most distinctive is Orion the Hunter. By early May, we’ll lose Orion in the setting sun, so April is the last chance to see this popular constellation until it reappears as a morning constellation in late July.
Follow the belt of Orion to the right and find Taurus the Bull and the Pleiades. Follow Orion’s belt to the left (lower down in the sky) and you’ll find Sirius, the Dog Star, in the constellation of Canis Major (Big Dog). Sirius shines much brighter than any other night star.
Above Orion and Taurus are the Gemini Twins and Auriga the Charioteer. The Gemini has twin bright stars, Castor and Pollux, named for the heroic twins of Greek mythology. Auriga’s bright star is called Capella. Also in this spring western sky you’ll find Procyon, the bright star in Canis Minor.
Leo the Lion is high overhead in the April evening sky. To the east of Leo is Virgo; while overall Virgo is a sprawling and rather faint constellation, it has one really bright star called Spica. Saturn appears fairly close to Spica this year.
In the northern sky, the famous Big Dipper is high in the northeast. The pointer stars of the Big Dipper — the two stars in the cup that don’t have the handle attached — point to the North Star.
The handle of the Big Dipper is bent, or has an arc to it. If you follow the handle, it points you to the bright star Arcturus (“arc to Arcturus” as the saying goes). Arcturus is partway up in the eastern sky on this map. You may know it better by its Hawaiian name, Hokulea (“star of gladness”); the famous voyaging canoe is named for the star.
Leo the Lion is also high overhead. Regulus marks the lion’s heart; the backward question mark that rises up from Regulus marks the lion’s mane.
Stars that aren’t on the map: The Southern Cross will rise at 10 p.m. in early April and by 8 p.m. at the end of the month. Look for the bright stars Alpha and Beta Centauri to the left of the Southern Cross; this can be your guide to point to the Cross itself.
Scorpius also rises later in the evening. Called Ka Makau Nui o Maui in Hawaiian, or “Maui’s Big Fishhook,” this massive constellation blazes brightly in the southeast at 1 a.m. at the start of April and 11 p.m. by the end of the month.
Mike Shanahan is the Bishop Museum’s director of education, exhibits and the planetarium. Visit www.bishopmuseum.org/planetarium/planetarium.html