As April begins, the moon is in its waxing gibbous phase, seen in the south before sunrise. Saturn is just off to the southwest. Mercury, visible in the dawn sky all month, is seven degrees south of the slender crescent moon April 7 and 8. These could be tough observations, since the angle of the ecliptic favours Southern Hemisphere viewers. On the evening of April 14, in the west, Jupiter will be within two degrees of the moon; April 24, the nearly full moon occults Spica for Southern Hemisphere observers, a very close conjunction for us in the north. The next day, the moon is full and a partial lunar eclipse occurs, but only for viewers in the Eastern Hemisphere.
Mercury is visible in the eastern morning sky throughout April. Watch for the close brush by the moon April 7, and within two degrees of Uranus April 19.
Venus is hidden in the sun's glare until very late in the month, when it begins its role as the Evening Star low in the west at sunset. May promises to be a better time to observe Venus.
Mars is retrograding behind the sun, and won't be visible again until early May.
Jupiter, visible in the constellation Taurus, in the west before sunset, joins the thin crescent moon April 14. This could be a great night for some astrophotography, with Orion off to the east, Jupiter and the moon among the stars of the Hyades and the Pleiades a bit further west.
Saturn rises in the east about the same time Jupiter sets, so we get to see both of the giant gas planets in the sky at the same time.
Uranus is back late in April in the pre-dawn sky. Watch for Mercury joining up with the blue-green gas planet April 19.
Neptune, a tough observation at best, is challenging because it's just rising ahead of the sun in the early morning. With the ecliptic almost horizontal, the planet rises nearly the same time as the sun does.
April 22 is the night when the Lyrid meteors peak. Some will show up anywhere between April 19 and 25, but the maximum rate of about 20 per hour (under ideal conditions) occurs April 22. The nearly full moon this year unfortunately makes the Lyrids hard to observe. This particular meteor shower originated with Comet Thatcher, which last passed through the inner Solar System in 1861. When the Earth's orbit encounters the dust particles, they streak across the sky as they vapourize in our atmosphere.
Finally, Comet Pan-STARRS is out there, but it isn't very bright and it disappears quickly with the sun. Some observers have taken long-exposure photos that show it up nicely, but the comet isn't a naked-eye object. An excellent photo by Alan Dyer can be found at http://spaceweather.com/gallery/indiv_upload.php?upload_id=79160.
- James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000 and is editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal, and the society's national secretary.
