It's Not Easy Being Green

The internet has been all a buzz about the "green comet" and falsely raising expectations of how it will appear in the sky.

So why are they calling it a "green comet"? That is a bit odd as all comets have a green glow about them as they get close to the Sun. I suspect that the real reason they are calling it the "green comet" is that its real name, C/2022 E3 (ZTF), is just too much of a mouthful to use and explain.

The comet has risen in brightness to the point where it can barely be seen without optical aid from a very dark sky. This is about as bright as it was expected to be, so all the hoopla about it being "bright" doesn't make much sense. Still, it looks pretty nice when photographed with a telescope.

The comet was discovered at Palomar Observatory in March of 2022. I first saw the comet August 30, 2022 when it was still more than two astronomical units from both Earth and the Sun. Here's how it looked then:

Comet C/2022 E3 (ZTF) 30 August 2022, taken with a Unistellar eVscope

 The comet and its tail are visible at the center of the image. 

I didn't observe it again until earlier this month when the comet was much closer to both Earth and the Sun. Here's a photo from early in the morning on January 12, 2023:

Comet C/2022 E3 (ZTF) 12 January 2023, taken with a Unistellar eVscope

That green color, which comes from ionized diatomic Carbon molecules, is now visible along with the whitish dust tail and a faint narrow ion tail. It is maybe easier to see the details in this animation which shows the comet's motion against the background stars:

 It has been a rainy and cloudy January and I didn't get a chance to observe the comet again until January 21st. 

Comet C/2022 E3 (ZTF) 21 January 2023, taken with a Unistellar eVscope

Again, the green glow of the comet's coma, the dust tail and ion tail are all visible, but with everything looking better than it did on the 12th. Here's an animated gif from images taken the morning of the 21st:

By January 26th the comet had moved far enough north that it was a circumpolar object, which meant that I didn't have to get up before sunrise to see it. Also, because the comet's position is changing relative to Earth, our view of the comet and its tails had changed. Below is a two-frame mosaic of the comet:

Mosaic image of comet C/2022 E3 (ZTF) 26 January 2023, taken with a Unistellar eVscope

I shot this mosaic to capture more of the comet's thin ion tail which was too long to fit in a single frame.

The comet will be closest to Earth in just a few days and when the weather clears I will try to catch it again.