The moon is new April 1, which means it is direct line of sight with the sun, or invisible. A couple of days later, it’s within 0.6 degrees of Uranus; an occultation in the Southern Hemisphere. April 6, the minor planet Ceres is within 0.2 degrees; another occultation, again in the Southern Hemisphere.
The moon is at apogee April 7 (404,438 kilometres). As expected, a little over 14 days after new moon, full moon occurs April 16. April 19, the moon is at perigee (365,143 kilometres). April 24 to 26, a rash of close encounters occurs, beginning with Saturn April 24, then Mars April 25, Venus April 26 and Jupiter April 27. What this means to the avid astrophotographer is close groupings of the bright planets – good reason for rising early to set up the camera gear.
April 30 brings the moon back around in front of the sun – but this time with a twist – it really is in front of the sun, resulting in a partial solar eclipse, visible only from South American countries or from shipboard in the Pacific or Atlantic oceans.
Mercury comes out from behind the sun about mid-month to begin the best evening apparition for Northern Hemisphere viewers. April 18, Mercury and Uranus are two degrees apart. April 29 finds the speedy planet among the stars of the Seven Sisters (The Pleiades). This is also Mercury’s greatest elongation east.
Venus has been close by Mars and Saturn for much of the previous weeks, and now begins to draw away from them. Toward the end of April, Venus encounters the moon April 26, Neptune April 27 (only 0.1 degree away), and Jupiter April 30 (a mere 0.2 degrees away).
Mars is in conjunction with Saturn April 4, separated by only 0.3 degrees and showing similar brightness, but differing colours. All month long, Mars and Saturn share the same bit of sky. The crescent moon passes by April 25.
Jupiter is in a close conjunction with Neptune April 12, but observing the event will be a particular challenge, owing to the brightness difference between the two planets. Around mid-month, Jupiter trails a lineup of the other three bright planets: Venus, Mars, and Saturn. This might be a good photo-op for the early riser – four planets equally spaced in the morning predawn. April 27, the moon passes by four degrees to the giant planet’s south.
Saturn, as mentioned above, is in conjunction with Mars April 4, is one of the four-in-a-row as given above, and watches the moon glide by April 24.
Uranus is almost occulted by the moon on April 3. April 18, Mercury is two degrees to the north, then Uranus fades into the evening twilight as the month progresses.
Neptune, while mainly a telescopic target, presents two close conjunctions, one April 12 with Jupiter, and the other April 27 with Venus.
James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000, was national president for two terms, is now the editor of Observer’s Handbook, and production manager of the bi-monthly RASC Journal. The IAU named asteroid 1995 XC5 “(22421) Jamesedgar” in his honour and he was recently awarded a Fellowship of the RASC.