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Keep tabs on our planets with Morrison Planetarium's quarterly guide to planetary activity.
The smallest planet is at inferior conjunction on April 1, located on the same side of the Sun as Earth and crossing into the morning sky. This won't be a very favorable predawn apparition for observers in the Northern Hemisphere.
The waning crescent Moon passes nearby on the morning of April 14, but this is too close to the Sun to be seen. Even at greatest western elongation on April 29, Mercury remains too low to be seen before dawn due to the shallow angle of the ecliptic (the line across the sky defining the plane of the solar system). The waning crescent Moon's passage very close to Mercury on the morning of May 13 will likewise be too close to the Sun to be seen.
Mercury continues inching into alignment with the Sun, passing superior conjunction behind our star on June 5. As it enters the evening sky, the ever-elusive little planet is joined by the Moon on the 13th & 14th, but this occurs too close to the Sun to be seen in the glare. Mercury finally creeps far enough out of the twilight to be seen in late June.
Already visible just after sunset, Venus is beginning its domination of the evening sky that lasts through September.
Setting 1-1/2 hours after the Sun on April 1, 2 hours after on May 1, and 2-1/2 hours after on June 1, Venus seems to linger at the same height above the horizon from night to night just after sunset, slowly traversing 108 degrees eastward from the stars of Aries through Taurus, Gemini, and into Cancer, during which time the entire sky rotates 90 degrees.
The Moon passes near Venus on the evenings of April 17, May 17, and June 15 and 16. On the evening of June 19, Venus is about a half-degree from the binocular "Beehive" star cluster in Cancer the Crab.
Mars rises 4-1/2 hours before dawn on April 1, 4 hours before on May 1, and 5-1/2 hours before on June 1.
The Red Planet has a very close conjunction with Saturn on April 2, when both are only 1.3 degrees apart. Then, Mars moves eastward from Sagittarius the Archer next-door into Capricornus the Sea-Goat, becoming stationary on June 28, when it stops moving from west to east and reverses its motion.
On the mornings of April 2 and 3, telescope owners can see Mars passing a half-degree from M-22, a globular star cluster just off the upper-left of the lid of the "teapot" asterism in Sagittarius.
The Moon passes nearby on the mornings of April 7, May 6, and June 3. More about Mars' approaching opposition in Notes.
The largest planet rises about three hours after sunset on April 1, about a half-hour after on May 1, and about two hours before sunset on June 1.
One of the most distant naked-eye planets, Jupiter plods slowly against the stars of Libra the Scales, moving only nine degrees against the stars this season—and in retrograde, at that, moving from east-to-west instead of in the usual west-to-east direction.
It's at opposition on May 8 (opposite the Sun and rising at sunset), making it easy to observe through the night.
The Moon passes very near Jupiter on the night of April 2, then again on April 29, May 26 and 27, and June 23.
Rising 4-1/2 hours before sunrise on April 1, 4-1/2 hours after sunset on May 1, and less than two hours after sunset on June 1, the Ringed Planet loiters all season against the stars forming the "teapot" asterism in Sagittarius the Archer.
Don't miss the 1.3-degree encounter with Mars on the morning of April 3, when both planets are visible in the same field of view in a pair of binoculars.
The Moon passes spectacularly close by on the morning of April 7, with Mars nearby as well. It passes Saturn again on the mornings of May 4, and June 1.
Saturn reaches opposition on June 27, rising at sunset and visible all night, when the Moon is again very close by.
Download the Morrison Planetarium's 2018 Pocket Almanac to stay up-to-date on eclipses, meteor showers, satellite spottings, and more.
The Benjamin Dean lecture series brings the world's leading experts in astronomy, astrophysics, and more to the Academy's Morrison Planetarium.