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Other things

I have done as little as possible this weekend. Partly because it has been really hot, and I don't do heat. But also because I've just felt shattered. No idea why, it's not as if I had a hard week at work. Okay, work was hard, but only two days of it...

When I came back home on Friday, I grabbed some wire wool and rubbed down the frames of the bedroom windows. Then on the outside, I threw on a coat of varnish. My window opened, mom's remaining closed (as I didn't fancy going into her room). My window is behind a shutter at night, but mom's has no shutter so it's been exposed to the elements for nearly two decades. The wood was rough and starting to split. I figured that something needed to be put on it.
Saturday morning, I gave the wood another coat of varish.

Newly varnished window

I also began scraping old white gloss paint off of the front door, but the heat was too much. That's something else on my to-do list, repaint the door (and possibly the living room windows).
These, I think mom painted, back in '97 (or so). A repaint is long overdue.


NEOWISE and other stuff

On Friday evening, I took my telescope out to catch a glimpse of the comet NEOWISE. The comet, actually, is called C/2020 F3. The NEOWISE moniker comes from the mouthful that is Near Earth Object Wide-field Infrared Survey Explorer, which is the satellite that disovered it. But like people like to call the current pandemic "coronavirus", this comet is called "NEOWISE" (in capitals) instead of the numerical gibberish. Because people like things to have names, not numbers or codes.
Might I suggest that we just simply call it "Julie"?


While waiting for it to get dark enough, I took a look at Jupiter:

Jupiter, Ganymede, and Europa.
I tried a number of different settings, but since Jupiter just appears as a dot, I didn't find an option that was able to resolve anything other than said dot. It would have been nice to see some of the surface features, it big enough that there are sufficient pixels that something should have been visible. But it's a bright dot to my eye and a bright dot to the camera. Maybe if I get myself a bigger telescope in the future...
It's Ganymede closest to Jupiter, and Europa to the right. The others (Callisto and Io) are either in front of or behind Jupiter at the time this photo was taken (2020/07/17, 22:52 CEST). There are 75 other moons, but they're too small to be visible.

My next target was a fainter dot just to the left of Jupiter. Yup, Saturn:

Like with Jupiter, this image has been rotated to be the right way up and zoomed in. Saturn is actually tiny in the eyepiece, even with a 2× adaptor in place (so, what, 50×?). Still, it's pretty impressive to be able to resolve the ring around a planet that's something like 1.3 billion kilometres away. Light, and radio signals, take a little under an hour and a quarter to travel from Saturn to Earth (or vice versa). That's how far away it is. I'd need a bigger telescope to do better. I think mine's maybe 3-4 inches? I'll need twice that.
And I'd need it before 2024 or after mid 2026, because for that period of time, the ring will be end-on to Earth (it wobbles).

I am low lying, and there are quite a number of trees to the north west. That makes spotting the comet rather difficult. So I did what any self-respecting nutter would go. I bundled the telescope into the boot and took off in my car to find a nearby field with an clearer view of the bit of sky that I wanted.
I didn't have to go far. Just down the access lane, turn left, round the bend, and carefully back into a field access. Here's a photo I've messed with (pushing the darks and shadows) so you can see...something. ☺

Parked in a field
I wondered what I'd say if somebody drove by and saw me. To my benefit, I could call up a wiki article on NEOWISE on my phone, and the telescope is pretty obviously a telescope.
But nobody came. Not a sound. Not a whisper. Well, it was approaching half eleven at night!

Frustrated at not seeing a damn thing, I snapped a photo of the sky to stick on my blog with the caption "not a bloody thing". An hour after sunset, my ass.

Empty sky...or is it?

I'll forgive you if you didn''t see it. But it's there. The camera caught something my eyes failed to detect. You see that long flat cloud along the bottom? There's a little dot of a cloud to it's right? Well, go from a point between the two clouds and head up about halfway.
I'll still forgive you if you don't see it. I looked at the photo several times to convince myself my eyes weren't fooling me, that it wasn't some artefact of the JPEG compression.

Convinced that there really was something there, I went out, set up my phone's camera to a ten second exposure, and let it take a photo.
The result? A beautiful shot of the Big Dipper with NEOWISE visible to the lower right just above the shadow of the trees.

Big Dipper and NEOWISE

The telescope view was less interesting. Distinction disappears as the many optical elements involved block light so the detail of the comet's tail is lost, and it appears like a spaceship rather than a comet because, well, that's how much it moves in a ten second exposure.

What is interesting is that it appears with a greenish hue. This is because comets are actually quite complex. As the outer parts of the comet heat up due to the sun, it not only reflects light just like the planets and moon, it also has two tails.
The first tail is a faint blue ion tail caused by the powerful UV from the sun ionising the carbon monoxide present in the comet. This blue tail always faces away from the sun, regardless of the comet's actual direction of travel.
As comets get close enough to the sun (roughly within the orbit of Mars), the comet heats up more. Comets out in far space are something like -220°C, and as they approach the sun, they will warm up. In 1986, the Giotto spacecraft measured Halley's Comet as having a surface temperature of 77°C. Combined with the blast of powerful UV, that's an insane temperature swing.
As the temperatures rise, the ices melt away to leave a region of diffuse particles made of gasses and dust around the comet, like a mini atmosphere. It's called the "coma". Now, a particle wrapping around the comet cannot help by be struck by the sun's radiation. The pressure of this happening pushes away the heavier particles, the dust, which is what creates the big grey dust tail that we're all familiar with. As it's basically stuff jettisoned from the comet, it traces the direction of travel and tends to expand out from the comet, like the exhaust of a polluting engine.
The final part is the coma itself. This occurs because as the comet heats, it isn't just dust and carbon monoxide. You'll often find hydrogen, oxygen, carbon, nitrogen... essentially the building blocks of stuff.
You'll also find two carbon molecules - cyanide (carbon-nitrogen) and diatomic carbon (carbon-carbon). Remember this the next time somebody suggests that life elsewhere in the universe may not be carbon based. It's possible. But given the strong prevalence of carbon compounds, it's likely that life (intelligent or not) will be carbon based like us. They just might look more like jellyfish than humans and they won't speak English.
Now, when these gasses and things are struck by the UV from the sun, it messes with the electron binding in a way that will require lots of senior/college level chemistry lessons to understand. Suffice to say, these electrons don't remain in their UV-enhanced higher energy state (technically known as "excited", whoo!). They will revert to normal so that the atom is in a balanced state. When this happens, the energy that 'excited' the electron needs to be released, and this happens by the emission of photons, some of which emit in the UV range, and some of which emit in the visible parts of the electromagnetic spectrum. Specifically green. Which indicates a lot of CN/C2 molecules being heated. It also indicates that there is potential for the comet to break apart due to its heating and behaviour.

NEOWISE will be making its way up along the bottom of the Big Dipper for the rest of the week. Tonight, the 19th, it should be near to the lower left of the 'pan' (Phecda). It's about as far from that star as the star is away from the upper star in the pan (Megrez). The only problem, it's getting dimmer, so if you want to observe the comet for yourself, do so now.

Ignore the advice saying "an hour after sunset". If you can't clearly see the stars of the Dipper (or Plough), then you won't clearly see the comet. My photos were taken around midnight, two hours after sunset.

A telescope or binoculars will be good for observing the comet with your eyes. For taking photos in the absence of proper cameras and telephoto lenses, you can get photos like mine out of a smartphone. It just needs to have a camera app with a "Pro" mode. Set it to an eight or ten second exposure, then leave the ISO setting on automatic or step it back if it passes ~800. This might sound counter-intuitive, however you're effectively trading time for sensitivity. If you push the ISO to 1200, 2400 or even further, there's a good chance you'll end up with a lot of noise and speckling in the photo. A ten second ISO 800 photo will be much better than a four second ISO 2400 photo.
Finally, mount the camera. If you don't have a tripod, arrange some rocks and place your phone (or camera) in position. Set a timed trigger (2 or 5 seconds) so you have to press the trigger and move away in order to get a clear picture. Android phones these days can respond to voice control - you can speak "smile" or "cheese" in order to take a photo. That's how I took mine. Completely hands off, no vibration, clear photos.

Have fun!

Comet and tail

All of the photos in this article were created using a Samsung S9 phone, and any editing applied using the built-in "Photo Editor Pro".



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David Pilling, 21st July 2020, 01:55
Good stuff, I was inspired to go outside - couldn't see it. Clouds, light pollution.

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