5 Sky Events This Week: Jovian Shadows, Lunar X, and Lord of the Rings

This true-color composite image taken on December 12, 2000, captures Jupiter’s moon Io and its shadow in transit against the cloud-tops of the gas giant. Backyard telescopes this week will be able to pick up similar shadows from the moons Ganymede and Europa. Credit: NASA/JPL/University of Arizona

Sky-watchers keeping an eye on the moon may spot a special lunar landmark this week, while Saturn, the magnificent ringed planet, appears at its best for 2014.

Jovian moon shadows. On Monday, May 5, look for Jupiter, the giant planet, to hang low in the western horizon at night. High magnification through small backyard telescopes will show Jupiter’s largest moon, Ganymede, as a tiny black dot gliding across the planet’s disk.

Start looking for the moon’s silhouette to cross the planet’s outline at 10:08 p.m. EDT. By 12:37 a.m. EDT, another major moon of Jupiter will join the party when Europa begins to cross the planet from the east. Although the gas giant will sink below the horizon before the moon transits are complete for observers in eastern North America, those in the west will see the entire transit.

Eta Aquarids peak. Before dawn on Tuesday, May 6, this minor meteor shower is slated to peak. Favoring observers in the Southern Hemisphere, a dark sky will offer as many as 20 to 30 shooting stars every hour. For sky-gazers in the north, expectations are for more modest numbers, 10 to 20 per hour in the early morning hours. The shower’s radiant (point of origin) appears very close to the southeastern horizon in its namesake constellation, Aquarius.

Lunar X. After nightfall on Wednesday, May 7, the moon will reach its first quarter phase. This represents the best time to catch sight of a unique lunar feature, one where X marks the spot.

The optical illusion of a giant X formation of the surface the Moon is visible around the 1st quarter moon every month.
The optical illusion of an X formation on the surface of the moon is visible around the first quarter moon every month.

On the moon at this time, a weird topographical formation will appear for only about  four hours—a letter X—visible with the smallest telescope or even steadily held binoculars. While it does look artificial, this conspicuous feature, called the “Werner X,” is actually formed by the walls of three craters clustered together. The optical illusion is seen when sunlight hits the rims of the craters at just the right angle while the crater floors are in total darkness. Not many have seen it because it’s visible for only a few hours each month.

Start your hunt for the lunar Werner X about a third of the way up from the heavily cratered, southern limb of the moon, along the terminator line (where light and darkness meet). You’ll find a good chart with observational details in this article.

Saturn prime time. On Saturday, May 10, Saturn reaches opposition—when the planet is directly opposite the sun from Earth’s perspective. That means Saturn will be especially bright because it will be at its closest to Earth for 2014, making this an ideal time to take a gander at the gassy planet.

Credit: NASA/JPL

During opposition, the “lord of the rings” rises in the east at sunset and sets in the west at sunrise. At midnight you will find it due south.

Shining like a brilliant, creamy-colored star in the dim zodiacal constellation Libra, the ringed planet is a tad brighter than the neighboring white star Spica, to its upper right, and orange Antares, which sits just below Saturn.

Making this a must-see sky target with a telescope is the fact that during opposition, the rings seem to surge in brightness because of sunlight directly backscattering through its countless ice particles. This should make for an awesome sight!

Red planet encounter. On Sunday, May 11, look for another bright evening planet, Mars, to have a close encounter with our moon. The two objects will appear within only 6 degrees of each other, a little more than the width of your three middle fingers held at arm’s length. This close proximity will look impressive with the unaided eyes, but will also make for a great photo opportunity, particularly in the early evening when the pair is still close to the eastern horizon.

Meanwhile, observers in the Southern Hemisphere will see an even better show since Mars will appear even closer, less than 3 degrees, from the moon.

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Changing Planet

Meet the Author
Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.