I just have to post these. Because they’re gorgeous. These images were posted to twitter a couple of weeks ago by Mike Brown, during an observing run at Keck.
First up, this is Uranus, taken with a narrowband infrared filter which Mike described as “a filter where sunlight is absorbed by the methane atmosphere. But the rings still reflect, so they remain bright.” Just look at the detail captured in those rings! I’m guessing it’s around 720 nm (which would put it just barely in the infrared), but I could well be wrong on that – Methane has a few notable infrared absorptions.
As impressive as the Uranus image is, the Neptune image is even cooler!
This is apparently taken using the same filter. What you’re seeing are reflective clouds high up in Neptune’s atmosphere. Thanks to those clouds, you can see a few storms on Neptune as knots of reflective cloud material. Precisely why a planet as distant from the Sun as Neptune should be so stormy is still a mystery waiting to be solved.
And if those clouds don’t contain methane, I wonder what’s in them to reflect the light. Water vapour, perhaps? Or maybe ammonia…?
Seeing images as impressive as these tempts me somewhat to switch fields and look at solar system objects!