As May begins, the very thin moon joins bright Venus and Mercury in the early morning sky, with Mars and Jupiter hugging the horizon. This could make a very picturesque setting for astrophotographers.
You must be early, though, because the sun rises around 6 a.m., quickly overpowering the planets. By May 7, the star cluster M35 is in the scene, 1.7 degrees away from the moon. Full moon occurs May 17. At the end of the month, we again see Jupiter, Mars, Venus, and Mercury clustered in the dawn sky with the very thin waning moon.
Mercury attains greatest elongation west of the sun May 7, grouped with the other three planets as given above. Then it begins to dive, each day getting closer to the sun, as it orbits away from us. Probably the best day for seeing the four planets together is May 11.
Bright Venus graces the morning sky for early risers, a beacon in the east. It will guide viewers to Mercury throughout the month, as the two are within a couple of degrees of each other.
Mars is retrograding and seems to pass Venus and Mercury quickly as month-end nears, reaching closest approach to Venus May 23. Then it pulls away each day, further and further from the bright planet.
Jupiter is following the same program, just a few days ahead of Mars. Jupiter's close approach to Venus is May 11, and it quickly glides westward each day in its retrograde motion. The thin waning moon passes Jupiter May 29.
Saturn rises in the east during daylight, and crosses the sky all night. With warmer evenings, this is a splendid target for telescopic observing. Nothing compares to seeing the ringed planet hanging against the black backdrop of space, surrounded by some of its brighter moons.
Uranus rises about 4:30 a.m. in the east ahead of sunrise, and crosses the sky during the day. It's a tough observational challenge, but possible with some optical aid.
Neptune rises about an hour earlier -a telescope is definitely required to view this distant planet.
School kids often want to hear about Pluto - "Poor Pluto!" Why was this tiny glob of mostly ice demoted from planethood? Well, it turns out it is still considered a planet, just a small one - termed a "dwarf planet." And, there are plenty more of them, which is why the decision was made to change the designation of these small bits of frozen methane, ammonia and water. We know of at least 1,000 such objects in the Kuiper belt (pronounced like "viper") beyond the orbit of Neptune, some as larger or larger than Pluto. The four largest dwarf planets are now classed as "plutoids" to honour Pluto, which is visible through a telescope, but difficult to discern from the background stars. The only way one knows which is the correct object is to monitor its activity over a few nights. Then it is apparent that one bright light is moving among the rest - that's how we know it is not a star, but a plutoid!
- James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000 and quickly became involved in the society. He is editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal, and is the society's national secretary.
