That’s here; that’s home; that’s us—the two bright objects in this picture are Earth and the Moon, imaged by NASA’s OSIRIS-REx spacecraft on January 17, 2018 from a distance of 39.5 million miles (63.5 million km).
This is about the distance between Earth and Mars at their closest points to each other (give or take about 6 million miles) or about 165 times farther away from us than the Moon.
“We came all this way to explore the Moon, and the most important thing is that we discovered the Earth.”
– William Anders, Apollo 8 Commander
On Christmas Eve, December 24, 1968, the Apollo 8 CSM entered orbit around the Moon and, after completing 4 full orbits, provided the three astronauts on board with an amazing sight: a blue Earth rising* beyond the Moon’s cratered limb. Commander Frank Borman spotted the scene first and, after taking a 70mm black-and-white photograph, was able to rotate the Command Module so Earth remained in view through the small windows while CM pilot Jim Lovell captured this famous image on color film. It was the first time any humans saw the Earth from the vicinity of the Moon…and it was also the first Christmas that astronauts spent in space.
“The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth,” Jim Lovell said.
On September 22 NASA’s OSIRIS-REx spacecraft made a “slingshot” gravity-assist pass by Earth in order to adjust the angle of its flight toward Bennu. Mission scientists took the opportunity to test out the spacecraft’s cameras with planned observations of Earth and the Moon, and I’m happy to report that everything worked out perfectly! Some of the first images shared with the public were of Earth from a distance of 106,000 miles; this one shows the Moon imaged from 746,000 miles away three days later on Sept. 25. It’s literally a view of the Moon we can’t ever get from Earth!
Today, August 21, 2017, the Moon briefly slid in front of the Sun, casting its shadow onto the Earth–the deepest part of which (called the umbra) passing across the United States from Salem, Oregon to Charleston, South Carolina. I arranged to be positioned at the latter location, and thus experienced for the first time solar eclipse totality from 2:46 to 2:47 and a half p.m. this afternoon. It was, as they say, a mind-blowing experience…if just in the sheer sense of seeing something entirely different happening to the usually very typical Sun in the middle of what would otherwise be a very typical day. (Except that it was neither of those.)
Below are some of my photos from the event.
Saturn’s largest moon Titan is often called an analogy to early Earth, with its thick, chemical-rich atmosphere and widespread system of flowing rivers and north polar lakes. But located almost a billion miles away from the Sun, everything on Titan is shifted into a completely different—and frigid—level of existence from that found on Earth. With surface temperatures of 300 degrees below zero F, the lakes are filled with liquid methane and what’s life-giving water here is literally solid rock there. Even the rain on Titan falls as oversized drops of ethane.
But even in this extreme cryo-environment it’s possible that life may right now exist…life relying on an entirely different chemistry than what’s possible on our planet.
Recently scientists have identified a molecule on Titan called vinyl cyanide, or acrylonitrile. To Earthly life acrylonitrile is toxic and carcinogenic; luckily for us it isn’t naturally-occurring here. But on Titan it is and apparently in quantity; it’s possible that vinyl cyanide, raining down from Titan’s atmosphere into its vast hydrocarbon lakes, could even help form methane-based cell structures in much the same way phospholipids do here.
The molecule (C2H3CN) has the ability to form membranes and, if found in liquid pools of hydrocarbons on Titan’s surface, it could form a kind of lipid-based cell membrane analog of living organisms on Earth. In other words, this molecule could stew in primordial pools of hydrocarbons and arrange itself in such a way to create a “protocell” that is “stable and flexible in liquid methane,” said Jonathan Lunine (Cornell University) who, in 2015, was a member of the team who modeled vinyl cyanide and found that it might form cell membranes.
Further evidence of life “not as we know it?” Read more on Ian O’Neill’s Astroengine blog here: Vinyl Cyanide Confirmed: Weird Form of Alien Life May Be Possible on Saturn’s Moon Titan and in a Gizmodo article by Maddie Stone here: Potential Building Block of Alien Life Spotted in Titan’s Atmosphere