BAN #241: Climate irony, Goodbye NEOWISE, Gravity’s slower than I thought

03 August 2020   Issue #241

[Spiral Galaxy M81 image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona]

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Climate change is real, y’all


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Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a short description so you can grok it

If you can take one more pic of the comet C/2020 F3 NEOWISE, then this is a good one to go out on:

[Credit: Keel and Schmidt]


This was taken by my old friend Bill Keel using the 1-meter Jacobus Kapteyn telescope on La Palma in the Canary Islands. It was processed by Judy Schmidt, and if you’re not familiar with her name by now just search this newsletter or my blog.

In a recent blog article I mentioned that NEOWISE was sporting a spiral pattern in its head, likely due to a vent on its surface spewing gas into space coupled with the rotation of the nucleus, creating a garden sprinkler effect. Here the effect is obvious, and incredible!

Bill took images in three filters: red, yellow, and blue (these are standard colors used by astronomers). The pattern was most obvious in blue and yellow, but barely visible in red. It’s tempting to say that means it’s mostly gas, which emits strongly in blue, and not dust, which reflects sunlight so is strong in yellow and red. But you have to be careful: Only a little bit of, say, carbon monoxide gas would glow very strongly in blue and could overpower dust even if there’s more dust than gas. You’d really need to get a detailed spectrum to understand what’s what here.

NEOWISE is about 130 million kilometers from Earth now and heading away. I think it technically may still be naked eye visible if you’re at a very dark site, but the full Moon would wash it out pretty completely. By the time the Moon isn’t a problem any more, the comet will have added another 30 million kilometers to its distance from us and will have dropped in brightness by a factor of 2 - 3. So I doubt we’ll be seeing many more photos of it.

We don’t get too many comets as bright and magnificent as this one, so who knows when we’ll see another. Such is the life of an astronomer; sometimes there’s nothing to do but wait and hope.

I learned a thing!

Wherein I learn a thing

As someone vocal about astronomy in public, I get a lot of questions about it from folks. Most of the time these are great questions, showing a desire for a deeper understanding of some issue or news item the person saw. I try to answer when I can, though it can be hard because the amount of time it takes to answer the question well enough is significant.

But then there are the other kinds of questions, ones that are simply factual in nature. Like, say, “how many moons does Jupiter have?”, or “how wide is the Sun?” I get these pretty often, and it’s a little frustrating because you can literally type them into your favorite search engine and get the answer instantly.

I got a question like that recently, and decided it might make for a good article here on the newsletter. So to make my point, I literally typed the question into Google so I could screenshot the answer and prove my thesis.

The question, in this case, was “How fast is gravity?” (I get this one pretty often, usually asking something like, “if the Sun disappeared would the Earth instantly be flung away?”).

So I opened up Google, typed it in, and got, well, this:


I could blame my pal and colleague Ethan Siegel for this. He wrote an article about the speed of gravity on his blog Starts With a Bang (it’s good, go read it!). But of course the problem is in Google’s crawler, which looked at “between 2.993 × 10^8 and 3.003 × 10^8 meters per second” and decided that all the characters before the “8” weren’t important.

I’d hope folks would know that number is probably not right if they searched on this; I’ve cycled faster than this and didn’t launch myself into space.

Still, my point is: Feel free to just search on factual questions, but then take a sec to think about it and make sure it makes sense. And if it doesn’t, rephrase your questions and try again.

But don’t email me asking about it. I’m busy using Google to google how google’s crawler works.

Blog Jam

What I’ve recently written on the blog, ICYMI

[An incredible Mars Express shot of the red planet’s north pole. From Thursday article.  Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO]

Monday 20 July, 2020: Earth's asteroid impact rate took a sudden jump 290 million years ago

Tuesday 21 July, 2020: Et tu, Vulcan? A volcanic eruption marked Julius Caesar's death with climate disaster

Wednesday 22 July, 2020: To Mars! Perseverance rover all set to launch on Thursday 30 July

Thursday 23 July, 2020: How about a scoop of cinnamon caramel Martian polar ice cream?

Friday 24 July, 2020: The nearby supernova no one saw

Et alia

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