Every day we Tweet out the images from NASA’s Astrophoto of the Day as our final tweet. These images are sometimes shots of the night sky from Earth showing things like the Milky Way, planets, the moon, or the auroras (Boreal and Australian), or just the stars. NASA also occasionally posts storm photography taking by storm chasers on Earth or satellites or astronauts orbiting Earth at some distance.
However, for the most part, the vast majority of images that NASA posts are images that only NASA could post. They’re images from the space telescopes that show distant galaxies, nebulae, the planets in more detail than any commercial scope could render, asteroids and comets, the sun and solar flares, and phenomena we didn’t dare dream was possible prior to the start of the Space Age.
So, how is NASA able to get these wondrous photos of things that aren’t just a little bit distant but so distant the amount of space between Here and There is impossible for the mind to conceive?
1) Space telescopes have REALLY big lenses — We’re talking lenses that are measured in meters and yards, not inches or millimeters. No human-wielded camera has the kind of optical power that one of these has (and humans who have a really hard time holding up a camera with a lens taller than they are).
2) Space telescopes have extremely precise lenses — The lenses you get for your camera are very precise but the lenses that NASA has built make your lenses look shoddy. That’s because the lenses for a space telescope have to be almost inhumanly perfect in order for that lens to observe distant lights unseen by the human eye.
3) Space telescopes can stay pointed at one place for a long time — On Earth, we’re subject to rotation. Once every 24 hours, we’re able to focus on (roughly) the same point of the sky. However, in space, telescopes can focus on the same part of the sky for weeks or months, allowing them to do the kind of long exposure photography that just isn’t possible on Earth.
4) Space telescopes work alongside a lot of other cool instruments — The photos we see on APoD aren’t the exact photos the telescope captured. Sometimes they’ve been colorized based on information gleaned from another instrument such as a radiation meter an infrared/ultraviolet imager. The colors are also added by a computer programmed to render them out in colors that the human eye would recognize if the human eye were capable of, you know, functioning as well as a space telescope.
Those are just some of the reasons why space photography (which should be distinct from astrophotography if you ask me) can do so many things that photographers on the planet’s surface can only dream about doing. If you’re an astronomer (or astrophysicist) or just a photographer, we’d love to hear your thoughts on astrophotography in the comments below!
— da Bird