Hunter's supermoon, giant Halloween asteroid, and dancing planets fill autumn sky

The October full moon arrived at 5:05 a.m. today (Tuesday) and is known unofficially as the Hunter's Moon (supposedly because its bright glow allowed indigenous North Americans extra time for the last hunts before winter set in).

It is also a so-called supermoon because our satellite is at one of its several closest annual approaches, or perigees, to Earth in its orbit, thereby appearing about 14 percent larger.

If you are an early riser tomorrow (October 28), look to the eastern sky just before dawn for a rare treat: you will be able to see three of our solar system's five visible planets—Mars, Jupiter, and Venus—rise high in the sky together (the other two planets visible normally without optical aid are Mercury and Saturn).

Mars and Jupiter will bookend Venus in the middle and slightly to one side, with the two bracketing planets appearing about 4.5 degrees apart above the horizon (the width of your little finger held at arm's length against the sky is about one degree).

But the heavenly body causing the most chatter is the asteroid 2015 TB145, dubbed the Great Pumpkin by NASA, which will pass by the Earth and moon early on Halloween.

The asteroid, only discovered by University of Hawaii researchers on October 10, is about 400 metres wide and will come to within 1.3 lunar distances of Earth, about 480,000 kilometres, close by astronomical standards. Nasa has announced that it doesn't pose any danger. (Potential observers would need at least a small telescope to observe the massive space rock.)

Lance Benner of NASA's Jet Propulsion Laboratory in California, said in a news release that the object has an unusual "very oblong" orbit.  "Such a unique orbit, along with its high encounter velocity—about 35 kilometers, or 22 miles, per second—raises the question of whether it may be some type of comet."

Meanwhile, looking ahead a week after Halloween, the waning Hunter's moon will appear in a conjunction with Venus and Mars in the early morning eastern sky of November 7. If the sky is clear, watchers will be able to compare the contrasting colours—white and red, respectively—of the two inner planetary neighbours. Use a good pair of binoculars for the easiest best effect.