An eclipse of a volcanic moon by the king of planets, Jupiter, will thrill stargazers this week, as Earth's moon rides above the ringed world, Saturn.
Moon meets Maiden. On Tuesday, January 13, early birds will enjoy a particularly close encounter with the last quarter moon of the month and with the bright star Spica. All the action takes place in the constellation Virgo, the Maiden, halfway up the southern sky at dawn.
The 250-light-year-distant star appears only 2 degrees below the moon, a distance equal to about the width of your thumb held at arm's length.
It's amazing to realize that the light from Spica left on its journey to Earth back in 1765. That's the year that Great Britain passed the Stamp Act, the first direct tax levied on the American colonies and a prelude of the parliamentary oversteps that led to the American Revolution.
Mercury at its best. Look for faint Mercury about a half-hour after sunset on Wednesday, January 14, just above the southwestern horizon.
The innermost planet will appear at its farthest point away from the sun, a moment called the greatest elongation. Sitting 19 degrees east of the sun, it would be challenging to track down its faint point of light if it weren't for the nearby, superbright Venus.
The planetary duo will appear only 1.3 degrees apart, making the pair particularly impressive when viewed through binoculars or a small telescope. Look carefully and you may notice that Mercury appears to be a miniature version of the half-lit moon. (For more Mercury news, click here.)
Volcanic moon eclipse. Sky-watchers armed with telescopes will witness a distant eclipse of Jupiter's moon Io in the early morning hours of Friday, January 16.
At 12:27 a.m. EST, the gas giant's own shadow will glide across the tiny disk of the volcanic moon, which will be visible to the west of the planet.
Also early on Thursday night at 10:56 p.m. EST, Jupiter's massive storm, the Great Red Spot, crosses the middle of the planet's disk. Appearing as an orange-pink oval structure, this hurricane circles the planet every 12 hours or so and is three times larger than the Earth. (Related: "Jupiter's Great Red Spot Is Shrinking.")
Luna and Saturn. Later on, near dawn on Friday, January 16, the waning crescent moon will appear to park itself just 2 degrees north of Lord of the Rings.
The ringed world can't be missed with the naked eye since it is the brightest object visible in the southeastern predawn sky. Its proximity to the moon will make it that much easier to identify.
Train a telescope on this yellow-tinged point of light, and it will readily reveal its stunning rings, tilted a full 25 degrees toward Earth. Currently Saturn sits nearly 994,000 miles (1.6 billion kilometers) away from Earth, which means that the reflected sunlight off its cloud tops takes 87.4 minutes to reach our eyes.