Look up tonight, August 27, and you'll notice two bright spots to the west that are incredibly close to one another. This is the closest those two particular features will appear in the night sky until 2065, and if you have binoculars or a telescope, you'll even be able to see them in the same field of view. One of those dots is the celestial version of hell—a rocky orb roasting at 850°F and shrouded in clouds of sulfuric acid. The other is, well, scientists aren't positive what it is—yet. Swirling, centuries-old windstorms likely wrapped around a giant ball of liquid metallic hydrogen. These dots even have names: Venus and Jupiter.
Just before sunset, look westward. The conjunction will become clear 30 minutes after sunset (in the northern hemisphere). Only the Sun and Moon are brighter in the skies of Earth, so you shouldn't have too much trouble finding Venus and Jupiter. Together they will form an impressive brightness in the sky. (How impressive? Over at Space.com, Joe Rao explores the theory that a conjunction of the two planets millennia ago might explain the Star of Bethlehem.) Together is a relative term, though: While from the perspective of Earth the planets will appear very near to each other, Jupiter is actually more than four times farther from Earth than Venus is.
So now you know when and where to look. But where to set up for the show? With the U.S. National Park Service celebrating its 100th anniversary this week with free admission to national parks across the country, it's the perfect time to get out and enjoy a true night sky. Even if you hate trees, mountains, dirt, nature—if you hate the planet Earth, basically—national parks are still the place to be for sky watching, because they offer more than Earth. Free of the scourge of light pollution, the sky over Badlands National Park or Rocky Mountain National Park (to name only two) is literally galactic, with the kinds of nighttime views of the Milky Way that can take one's breath away. Many parks host telescope viewings, with rangers pointing out celestial features above.
GETTING CLOSE TO THE LARGEST PLANET
Our view of Venus isn't the only thing getting close to Jupiter this week. NASA's Juno spacecraft is presently in orbit around Jupiter, though not, as you might imagine, circling it. In fact, the shape of the orbit is more like an extreme oval, with the spacecraft getting really close to the planet and then zooming far away. Why? Because the Jovian system is surrounded by punishing radiation belts that would fry any spacecraft that hung around for too long. Elongated orbits allow Juno to dip into the radiation, get really close to Jupiter, scan it, and then fly out to safety before the radiation belt —and its particles zipping around at nearly light speed—can do their worst.
This morning, Juno reached "perijove," the closest it will get to Jupiter during its prime mission. A mere 2500 miles from the top of Jupiter's turbulent clouds, this is the first time Juno had its science instruments running during a flyby of Jupiter. (Previously, the instruments were off during closest approach because scientists at the Jet Propulsion Laboratory and Southwest Research Institute didn't want to interfere with the rocket burn and establishing Juno's perilous orbit.) The spacecraft today swept over Jupiter at 130,000 mph. Data will be sent back to Earth and studied by planetary scientists. The findings will be released in the months and years ahead.
Image credit: screencap of Science at NASA's "ScienceCasts: A Spectacular Conjunction of Venus and Jupiter"