Spectacular Sky Show: Venus, Jupiter and the Moon

The most spectacular celestial sights over the next couple of weeks are reserved for the early morning sky. Two bright planets will converge, then be joined by the moon.

Kenneth L. Franklin (1923-2007), the former Chairman and Chief Astronomer at New York's Hayden Planetarium, would often make reference to our "dynamic and ever-changing sky."

Such an eloquent description certainly fits our current morning sky, for these final days of January and the first days of February will be an exceptional time for predawn sky watchers with a beautiful pairing of the two brightest planets, Venus and Jupiter. They will appear closest together in the dawn sky of Friday, Feb. 1, and a few mornings later, the waning crescent moon will later drop by to join them.

Dazzling "double planet"

For the past several months, dazzling Venus has been prominent in our morning sky. And about a week ago, brilliant Jupiter also began to emerge from out of the glare of the Sun.

The two planets are currently rising out of the east-southeast horizon about two hours before sunrise.

From now through the end of January, the gap between the two will noticeably close, until on Feb. 1 they'll be separated by just over one-half degree, which is roughly the apparent width of the moon (The width of your fist, held at arm's length roughly corresponds to 10 degrees). Jupiter will shine brilliantly at magnitude -1.9, yet it will appear only 1/7 as bright as Venus, which will gleam at magnitude -4.0.

Together they will make for a spectacular "double planet" low in the dawn twilight. In the mornings thereafter they will appear to slowly separate, but before they have a chance to get too far apart the moon will join the picture.

Celestial summit meeting

At last quarter (half) phase on Jan. 30, the moon will stand alone, high toward the south at sunrise. But with each passing morning, as it wanes to a slender crescent, it will shift toward the east, ultimately into the same region of the sky as our two planets.

Early on Sunday morning, Feb. 3, the moon will sit well off to the west (right) of the planets. On the following morning, Monday, Feb. 4, the show will reach its peak when, about 45 minutes before sunrise, Venus, Jupiter and the moon — the three brightest objects of the night sky — will form a striking isosceles triangle, with the two planets 3 degrees apart and the moon marking the vertex of the triangle just over 5 degrees below the "dynamic duo."

Imagine the astrological significance that the ancients might have ascribed to a celestial summit meeting such as this!

You might want to check your southeast horizon in advance to make sure that there are no tall trees or buildings that might obstruct your view of the moon which will be sitting very low to the horizon.

Like a painting, this celestial tableau might, at first glance may appear rather flat and one-dimensional. But by gazing at this scene long enough, our minds can perhaps picture these objects strung out across the solar system, along our line of sight as they really are.

Beyond our moon — figuratively a stone's throw away at 247,000 miles (397,000 kilometers) — we first reach Venus, about 510 times farther out, or 126 million miles (203 million kilometers) from Earth. The lesser gem flanking Venus — Jupiter, largest of all the planets — is nearly 4 and a half times more distant than Venus at a distance of 560 million miles (901 million kilometers).

Generally speaking, at least for the immediate future, conjunctions between Venus and Jupiter will come in pairs. The first conjunction takes place in the morning sky, followed about 10 months later by another in the evening sky. Then, after about two and a half years, Venus and Jupiter are again in conjunction, again in the morning sky.

When Venus and Jupiter next get together, it will be in the evening sky late next fall, on Dec. 1. After that, we'll have to wait until May 2011 (morning sky) and Mar. 2012 (evening sky) for the next set of Venus-Jupiter conjunctions.