The month opens with the moon four days away from full phase. It cuddles up to the bright star Spica and Saturn, the ringed planet, June 1. A full moon is an opportunity for an eclipse, as is a new moon. If the orbits line up just right, as happened at last month's new moon May 20, a solar eclipse happens. Two weeks' passage presents another opportunity, and a partial lunar eclipse is what we will get with June 4's full moon. It will hardly be noticeable, though, since only a small part of the moon enters Earth's shadow. Western North America gets the best view, with the moon setting during the eclipse for us here in the prairies.
The asteroid Pallas is less than a degree from the moon June 12, an occultation for viewers in the northern Pacific and Arctic Oceans. Jupiter is occulted by the moon for northern Canada viewers June 17; and Venus is within 2 degrees that same morning. At month's end, Spica and Saturn hover close by again.
Venus has been on a descending track, getting closer to the horizon each day at sunset. By June 5, the bright planet is directly in front of the sun - a rare event termed a "transit." This will be the only transit visible for people living now - a once-in-a-lifetime event. The last one was June 8, 2004 and the next comes Dec. 11, 2117.
Much like the moon, Venus's orbit is tilted slightly with respect to the ecliptic, so transits don't happen every time Venus is this side of the sun. Earth and Venus are in resonant orbits - for every 13 Venus orbits, Earth makes eight - so transits occur on a predictable schedule of 105.5 years, 8 years, 121.5 years, 8 years, 105.5 years, and so on.
Warning: Transit viewers must use special protection to prevent harmful infrared and ultraviolet rays from damaging their eyes. Don't rely on homemade filters. Goggles are being made widely available through various outlets, either as a free handout or at minimal cost. (I have a small supply; contact me for a pair of free goggles.)
Mars is moving through Leo on its eastward orbit, getting further away from Earth with each passing day. At its great distance, surface features are hard to distinguish, even with a telescope.
Jupiter has been passing behind the sun for the past month, and the giant planet reappears in the dawn eastern sky early in June. As described above, June 17 finds Jupiter a little over 1 degree away from our satellite, occulted for northern observers.
Saturn doesn't appear to move much, and has been near Spica for most of the year. It continues throughout June, visible all night in the southern sky.
Uranus and Neptune are in the eastern morning sky, Neptune rising first in Aquarius, then Uranus follows in Pisces.
The summer solstice occurs late-afternoon June 20.
- 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 the Observer's Handbook, production manager of the bi-monthly RASC Journal, and is the society's national secretary.
