Astronomy and Space

[Martin Y]

Now I'm trying to remember when it was we showed the kids an impressive display of sunspots. The morning sun just happened to be shining through the stairs landing window onto the white-painted kitchen door about 5m away, so I stood at the window holding the binoculars (one lens capped), projecting the sun's image onto the door. I think the kids were almost as impressed at the sight as we were. Eeh, must have been 15+ years ago.

Daughter and I were sitting out in the garden last night watching Perseid meteors (and at one point rather excruciatingly pretending neither of us could hear the neighbours having noisy sex) and I did think the light pollution/haze seemed to come and go rather quickly; much faster than light cloud would pass over. I failed to put two and two together and realise it was probably the aurora.

[Gfamily]

Now I'm trying to remember when it was we showed the kids an impressive display of sunspots. The morning sun just happened to be shining through the stairs landing window onto the white-painted kitchen door about 5m away, so I stood at the window holding the binoculars (one lens capped), projecting the sun's image onto the door. I think the kids were almost as impressed at the sight as we were. Eeh, must have been 15+ years ago.

I read that there were over 200 sunspots on the visible face of the sun over the weekend. This is the most there has been for over 20 years.
Given that the solar sunspot cycle is about 11 years, it would most likely to have been nearer 20 than 15 years.

[Gfamily]

A bit - what? what!
https://x.com/tw__astro/status/1829495132791648518

[IvanV]

A recent (April 2024) discovery by the Juno spacecraft that has only just come to my attention is Steeple Mountain on Io.

An incredibly narrow and sharply pointed mountain, with a prominence of 5000m to 7000m above the surrounding surface, isolated a long way from other mountains in extensive flat plains, it looks like something out of a sci-fi art graphic, not something that could actually be real. I can't imagine the geological processes that can create such a formation. Moreover, it must be rather unstable. I wonder how quickly such things form and the collapse. We can see a lot of landslide debris around the base.

You can see a "fly-around" view of it if you click the short animation on the Wikipedia page here.

Smaller planetary bodies with weaker gravity enable taller mountains to form than on earth. The tallest mountain on Io is about 17,500m. The mountains of Iapetus, a moon of Saturn, are quite extraordinary - it has an equatorial ridge 1,200km long, generally about 13,000m high with individual peaks to 20,000m, on a moon of 1,500km diameter.

Which makes it a little odd to learn that Io has relatively flat relief in comparison to other major Jovian moons, despite all the volcanism throwing lava around, seemingly creating relief. There may be some very big and very pointy mountains, but much of the moon has extensive plains. Craters and valleys tend to get filled up with lava. It may also be that mountain ranges are not as well supported by the underlying crust as you would expect for the amount of gravity, given the tendency of the crust to melt into lava.

[Gfamily]

I managed to get this published in an astronomy magazine - two half images of the Sun, taken in late June (close to the time when the Earth is furthest from the Sun) and in January (close to the time when it's closest).

About 3% difference in size

Perihion and Aphelion.png (323.96 KiB) Viewed 6882 times

I have plans to repeat this in May and December with the Moon

[dyqik]

What's the difference from May to December?

[Gfamily]

What's the difference from May to December?

About 16% at full moon.

[dyqik]

What's the difference from May to December?

About 16% at full moon.

(I mainly posted to reference the BBC sitcom)

[Gfamily]

What's the difference from May to December?

About 16% at full moon.

(I mainly posted to reference the BBC sitcom)

Like the full moon, that went over my head (never found it much of a 'com')

[Grumble]

I managed to get this published in an astronomy magazine - two half images of the Sun, taken in late June (close to the time when the Earth is furthest from the Sun) and in January (close to the time when it's closest).

About 3% difference in size
Perihion and Aphelion.png

I have plans to repeat this in May and December with the Moon

I love that, hope the moon photo gets published too

[nekomatic]

On whether humanity will colonise Mars (Spoiler: No)

[Martin Y]

Latest attempt to put Wallace and Gromit's gas oven on the moon has arrived but it may be having a lie down.

https://www.bbc.co.uk/news/articles/c871eeez0yzo

[jaap]

I took a quick picture of the partial solar eclipse, using a sheet of paper with a pinhole to project it onto another sheet.

bafkreifyugmodiiqcodwcvrgbzo5buvzf3bx4i5pjne5wjpakq7rjonxhy.jpg (279.6 KiB) Viewed 2163 times

[IvanV]

I did it with a pair of binoculars rather than a pinhole, get a larger and more focused image, but still only about 15mm across.

[Gfamily]

We were obscured by clouds, but captured a sequence showing the dark side of the moon with the smart telescope

bafkreifyv4dqgvsp6lbjkjss2i3xm7tqhbxbllrw4v7xmkdejpb66kiwiy.jpg (61.49 KiB) Viewed 2153 times

Gave away almost 50 pairs of eclipse glasses too

[jimbob]

https://youtu.be/sPRr4DgMTxI

Cambridge University video by Professor Nikki Madhusudhan (leader of the team involved) about why they think they have discovered the strongest hints of biological activity outside the solar system

[dyqik]

https://youtu.be/sPRr4DgMTxI

Cambridge University video by Professor Nikki Madhusudhan (leader of the team involved) about why they think they have discovered the strongest hints of biological activity outside the solar system

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

[jimbob]

https://youtu.be/sPRr4DgMTxI

Cambridge University video by Professor Nikki Madhusudhan (leader of the team involved) about why they think they have discovered the strongest hints of biological activity outside the solar system

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

I can think of several ways that could be, but in what ways is it weak?

[monkey]

https://youtu.be/sPRr4DgMTxI

Cambridge University video by Professor Nikki Madhusudhan (leader of the team involved) about why they think they have discovered the strongest hints of biological activity outside the solar system

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

I can think of several ways that could be, but in what ways is it weak?

Heard a lady on the radio this morning who basically said "We have detected methane on mars, but that don't mean there's cows there."

Phil Plait (of badastronomy) did a thread on bluesky, he links to a few others who he says know more than him in it - clicky. They point out stuff like they can't be sure that the molecule detected was made abiotically, and you'd expect more molecules associated with life to be there, if there was life.

But it seems to me that it's another case of journalists being unable to tell the difference between "could be [insert thing here]" and "[insert thing here]".

[dyqik]

https://youtu.be/sPRr4DgMTxI

Cambridge University video by Professor Nikki Madhusudhan (leader of the team involved) about why they think they have discovered the strongest hints of biological activity outside the solar system

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

I can think of several ways that could be, but in what ways is it weak?

At the most fundamental level, it's a 3 sigma detection of DMS, when 5 sigma is the default for claiming a real detection.

Claiming that DMS must be a signature of life is very wrong. DMS has been detected in comets and the interstellar medium, and it definitely didn't come from life there.

[dyqik]

But it seems to me that it's another case of journalists being unable to tell the difference between "could be [insert thing here]" and "[insert thing here]".

The journalists here have been much more circumspect than the university press release or the public statements by the team. Their paper, on the other hand, is extremely cautious.

[jimbob]

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

I can think of several ways that could be, but in what ways is it weak?

At the most fundamental level, it's a 3 sigma detection of DMS, when 5 sigma is the default for claiming a real detection.

Claiming that DMS must be a signature of life is very wrong. DMS has been detected in comets and the interstellar medium, and it definitely didn't come from life there.

Ok so on two pretty important levels. I guess 5 sigma is chosen because it's the screening problem without any other prior probabilities known?

[dyqik]

I can think of several ways that could be, but in what ways is it weak?

At the most fundamental level, it's a 3 sigma detection of DMS, when 5 sigma is the default for claiming a real detection.

Claiming that DMS must be a signature of life is very wrong. DMS has been detected in comets and the interstellar medium, and it definitely didn't come from life there.

Ok so on two pretty important levels. I guess 5 sigma is chosen because it's the screening problem without any other prior probabilities known?

You can detect spectral lines with fairly high certainly at 3 sigma above the noise, as long as you have a reasonable expectation that that molecule is present, that the conditions are correct to produce that line, that the Doppler shift is right, and a confounding line is not contributing to that spectral bin (i.e. you have a high enough resolution and you have a good control of your background)

Several of those do not apply in this case, but it could well be a real detection. But it's certainly not enough to then reason from the fact of that detection.

[jimbob]

That makes sense, thanks

[discovolante]

Unfortunately, it's largely a weak result that has been massively overhyped by the team and University.

I can think of several ways that could be, but in what ways is it weak?

At the most fundamental level, it's a 3 sigma detection of DMS, when 5 sigma is the default for claiming a real detection.

Claiming that DMS must be a signature of life is very wrong. DMS has been detected in comets and the interstellar medium, and it definitely didn't come from life there.

Where does DMS in the interstellar medium and comets come from?