Astro Bob: Artemis captures rare Earth eclipse from moon's far side
Here's something you don't see very often: the moon eclipsing the Earth! We also preview a new, multi-part lunar mission launching Wednesday, Nov. 30.
If you've ever wanted to see an Earth eclipse from the far side of the moon, imagine no more! Here's what it looks like.
We all knew that NASA's Orion spacecraft would travel to a remote location in deep space some 40,000 miles (64,000 kilometers) "above" the lunar far side. But did anyone expect the alignment to be precise enough for an eclipse to occur? Probably. But I sure didn't know! What a welcome surprise and a perfect example of why we go to space in the first place: to encounter the unexpected.
There are a few fun things to note in the images. First, the colors. Look at how gray the moon appears next to Earth. Not only does the comparison demonstrate the moon's monolithic nature as a rocky, airless body, but also how much darker it is than our planet. Seen from your home in a dark, clear sky, the moon shines brilliantly, but when the two bodies are viewed side by side, the moon can't hide the fact that it's charcoal gray compared to our scintillating blue planet.
Take a look at the phase of the Earth. At the time of the livestream, the moon was a thick crescent in the evening sky. Seen from the moon, the Earth also undergoes phases, but they're complementary to those of the moon. That's why our planet is in gibbous (three-quarters) phase in the photos.
In the coming nights, Earth's phase will wane to half and then a crescent. At the same time, the moon will wax to half, then gibbous and finally full. On Dec. 7, when the moon lies directly opposite the sun and shines big and full for us, imaginary moonlings will look back toward the Earth and see it nearly in line with the sun in new phase. Just like a New Moon, where the lunar near side is fully in darkness, the New Earth would also be dark, an ideal time for telescopic observers to observe the planet's glowing cities at night.
Finally, you might be wondering how the moon can eclipse a planet four times its size. Consider that Orion was only about 40,000 miles from the moon but some 280,000 miles (450,000 kilometers) from the Earth — seven times farther away — at the time of the video. The closer you are to something the bigger its apparent size. Orion's proximity to the moon made it look larger. At the same time, the spacecraft's much greater distance from Earth "shrunk" our planet enough to make their apparent sizes nearly match.
Orion will soon head back toward the moon and perform an engine burn at low altitude over its surface, slingshotting it back toward Earth. Splash down in the Pacific Ocean is expected Dec. 11.
The focus on Earth's only natural satellite continues. SpaceX will launch Hakuto-R on Nov. 30, a private Japanese moon mission that will land a United Arab Emitates (UAE) rover weighing just 22 pounds (10 kilograms) on the lunar surface sometime next April.
The lander, Rashid , is equipped with several cameras: two to take detailed color images of the lunar environment, one for close-up, microscopic photos, and a thermal imaging camera to measure variations in heat rising from the moon's surface. It also has an instrument to measure the lunar electrical environment to figure out why moon dust is so "sticky." The information gleaned will help in designing better spacesuits for future moon explorers. The Apollo astronauts constantly dealt with lunar dust getting into everything including their lungs.
Rashid will land in Atlas, a 54-mile-wide (87 kilometers) crater in the moon's northern hemisphere, descending 1.25 miles (2 kilometers) to its floor. The mission will be brief, lasting from lunar sunrise to sunset, equal to 14 Earth days.
Liftoff from Cape Canaveral is scheduled for 2:39 a.m. CST on Nov. 30. If you can't get to bed because you're just too excited about so many missions now focused on the moon, stay up and watch the launch live on YouTube .
Hakuto-R will also carry NASA's Lunar Flashlight , a satellite the size of a briefcase that will hunt for water ice inside craters near the moon's south pole using four infrared lasers. The probe will fly within 9 miles (15 kilometers) of the polar surface and beam its lasers into craters where previous lunar missions have found indications of water ice bound inside lunar rocks.
Flashlight uses near-infrared lasers (light just beyond the red end of the rainbow spectrum) because water readily absorbs that wavelength, giving itself away. If the lasers strike bare rock, the on-board reflectometer will measure no absorption and therefore no water. But should the lasers strike water-rich rock, some of that light will be absorbed, indicating the presence of ice. The greater the absorption, the more ice may be at the surface.
Enjoy the nights ahead — I suspect your week won't be as busy as the moon's!