Usually you hear people talking about the other side of the moon — but what about the sun? Our orbit around the star means one side is out of view, but NASA’s Solar TErrestrial RElations Observatory Ahead spacecraft has been collecting images of the side we can’t see right now.
This image was captured on July 15 by STEREO-A while it orbits the far side of the Sun. NASA explains what it’s doing there:
STEREO-A has been on the far side of the sun since March 24, where it had to operate in safe mode, collecting and saving data from its radio instrument. The first images in over three months were received from STEREO-A on July 11. The three-month safe mode period was necessary because of the geometry between Earth, the sun, and STEREO-A. STEREO-A orbits the sun as Earth does, but in a slightly smaller and faster orbit. The orbit ensured that over the course of years, Earth and the spacecraft got out of sync, with STEREO-A ending up on the other side of the sun from Earth, where it could show us views of our star that we couldn’t see from home. Though the sun only physically blocked STEREO-A from Earth’s line of sight for a few days, STEREO-A was close enough to the sun — from our perspective — that from March 24 until July 8, the sun interfered with STEREO-A’s data transmission signal, making it impossible to interpret.
As STEREO-A kept orbiting, it eventually made its way far enough from the sun to come out of this transmission dark zone. In late June, the STEREO-A team began receiving status updates from the spacecraft, confirming that it had made it through its long safe-mode journey unharmed.