Last week, NASA gave us a small cosmic gift — releasing a short GIF of the Moon passing in front of Earth. The GIF was made from a compilation of images taken by the Earth Polychromatic Imaging Camera (EPIC) on the DSCOVR satellite, located 1 million miles from Earth. DSCOVR is meant to observe Earth's climate from afar and gives us a view of our planetary system we don't often see.
But some people just can't accept the good things in life. Many who saw the GIF immediately cried foul, saying they were certain the images were faked.
@NASA @NOAASatellites Haha, so fake!— Andrew ✌ (@amshiraah) August 5, 2015
@NASA @SwiftOnEconomy @NOAASatellites People actually believe this crap?— Legbiter (@BiteLeg) August 5, 2015
@NASA since when does 'epic' mean 'photoshop'?— PeskyMedia (@peskymedia) August 5, 2015
To be fair, who can really blame them? We live in a Photoshop-manipulated world. People are constantly trying to trick us into thinking that flood waters bring sharks to neighborhood streets or that today is the day Marty McFly goes forward in time. (It's October 21st, 2015 — never forget that!) A healthy dose of skepticism is a valuable asset in an era like this.
But you'd think there'd be more trust in NASA — a space agency that has landed 12 people on the Moon, launched more than 130 Space Shuttle missions, and just recently sent a probe to a dwarf planet 4.67 billion miles away.
Then again, a lot of people don't believe any of that stuff happened either. Sigh. Well, I may not have the strength to debate the Moon landings with anyone right now, but I can offer up some explanations about this GIF. Then we can all enjoy it as we should, because it's great and sometimes we can have nice things.
@NASA @NOAASatellites Why wasn't there a solar eclipse when this was shot? If the moon comes between the earth and sun, that is an eclipse.— Astro Answers (@skip_morrow) August 5, 2015
When these pictures were taken, the Sun was not directly behind the satellite. In fact, NASA purposefully keeps DSCOVR at least 4 degrees away from the Sun-Earth line — the direct path between our planet and the star. It allows researchers to more easily receive the satellite's data. "The sun is a powerful radio source and any spacecraft sitting in front of the sun would have difficulty communicating with Earth," Adam Szabo, one of the DSCOVR project scientists, tells The Verge in an email.
When the Moon is between DSCOVR and Earth, it's not actually between the Sun and Earth and no eclipse is seen. However, if you're into that sort of thing, the next scheduled solar eclipse is coming up on March 2016.
@NASA @NOAASatellites So disappointing. This totally looks like a simulation, the clouds do not move over the course of 6 hours?— Almanac Zach (@AlmanacZach) August 5, 2015
According to Szabo, that also puzzled the researchers for a bit. "The answer is lack of spatial resolution. The smallest features we can resolve are 8 to 10 kilometers at the center of the disk and many times more toward the edge. So the fastest clouds would move only a couple of pixels during six hours, and they actually do."
Cloud shapes are actually fairly constant, so while their absolute position may change relative to the surface of the Earth, their larger overall structures remain intact.
@NASA @NOAASatellites Why doesn't the moon spin like the earth?— Les Weidner (@LesWeidner) August 6, 2015
The Moon is tidally locked with Earth, meaning the Moon rotates on its axis about the same time it revolves around Earth. One side of the Moon faces our planet at all times, and the other side faces away. These images actually give us a view of the mysterious "far side" of the Moon. Here's a fun GIF of what that looks like: The Moon on the left is tidally locked while the Moon on the right doesn't rotate.
The reason we don't see at least some rotation is that these images only span about six hours. It takes over 27 days for the Moon to circle the Earth. During the course of this GIF, the Moon has completed only a tiny percentage of its orbit, so we see very little change.
@NASA @Canine_Rights @NOAASatellites Alright guys - Pink Floyd 'Dark Side of the Moon' is perfect behind this video ... yep ;)— norsepast (@norsepast) August 6, 2015
Totally agree. Just remember, we're looking at the far side — not the dark side. If it were the dark side, it'd be in shadow.
@NASA @NOAASatellites Someone told me there are cities on the Moon, and. Mars.— M. CoCo Saavedra (@bethghost) August 5, 2015
@NASA @NOAASatellites Shouldn't Earth look way smaller, since the distance between them is huge and the camera is closer to the moon?— Carlos Delfín Macías (@delfilmes) August 5, 2015
Sure DSCOVR is closer to the Moon than it is to Earth, but not by much. The Moon is 238,900 miles away from Earth, but DSCOVR is a whopping 1 million miles away. The satellite is nearly 800,000 miles away from the Moon when it passes in front of the planet. From that distance, it's almost like the Earth and the Moon are right next to each other when EPIC zooms in with its giant telephoto lens.
Here are some photos that illustrate this:
Additionally, the Earth does kind of look smaller if you think about it. In reality, the Moon is one-fourth the size of Earth, but in this image the Moon looks much bigger than that. Here's how the Earth and Moon compare to each other if they were side by side.
@nasa @noaasatellites EPIC! Worthy of its name— CP (@coldplague) August 5, 2015
Indeed it is, CP. Indeed it is.
Correction 2:41PM ET: This article previously suggested that the camera's focal length manipulated the sizes of the Earth and the Moon. It's only distance that changes the perspective, and the text has been updated.
Verge Video: The biggest discoveries from Pluto's flyby