Mars is bigger than the Moon. It’s just much much further away. But it can be bigger than the Moon if you point your telescope at Mars.
2 Likes
Insert obligatory Douglas Adams quote about space here.
6 Likes
4 Likes
And here I thought it was a long way to the pharmacy chemist.
ETA: Oh. NM. You added the quote. Or it finished loading after I started typing. Not sure which. But, yes, knew it instantly.
(I’ll have to watch Vader’s TED talk later.)
2 Likes
Interestingly enough, though, unless you have a good telescope, even in a telescope, it will still look smaller than the Moon. I mean, Mars isn’t even twice the size of the Moon, but as far as distance, it’s far more than twice as far away.
4 Likes
I much prefer the sign I made using the old WigFlip demotivator generator to most of the ones you find online (seeing the small Earth from the Moon really drives the point home), but it took me a couple of minutes to find where I’d stashed it.
2 Likes
Something like 142 times as far away when Mars is at its closest (opposition?), by my calculations.
2 Likes
Yeah, I was feeling too lazy to look up the distance. So I just went with vague. 
2 Likes
See Douglas Adams quote, above. 
2 Likes
On JWST disinfo: It’s also frustrating on YouTube once you let it know you’re interested. Some are mostly clickbait like “Shocks the Entire Space Industry!” “Breaks Modern Theories” etc.
But then there are the ones mentioning JWST along with “Terrifying NEW Discovery”, “Artifical Lights on Proxima B”, even promo images showing arrows pointing to a rocky planet/moon image with overlaid text, “There’s Life -->”. Nonsense based perhaps on purposeful misinterpretations of a paper wondering if wavelengths of artificial (LED) light are possible to detect, for example.
There’s even “Is JWST Permanently Damaged by an Asteroid?” with an image showing mirror destruction the size of four mirror segments, overlaid with text “End of Mission!? -->”. Sigh.
At least you can use each item’s “ ⋮ ” menu to tell YouTube “Don’t recommend channel” so you should never have to see such trash again.
6 Likes
5 Likes
You buried the lede! This is amazing!
That’s honestly one of the most beautiful astronomy photos I’ve ever seen.
13 Likes
Yes, but look at the treasure buried with it!
5 Likes
I was just coming here to gush about this image. It’s absolutely gorgeous!
4 Likes
It’s definitely on a short list with Cassini’s backlit photo of Saturn (with Earth, Mars and Venus photobombing).
(labeled version here)
4 Likes
Tax dollars very well spent.
5 Likes
That is a stunning image. I understand that lots of space telescope images are in infrared (or somewhere near it) because it lets us peer through dust clouds and whatnot, but I also hear a lot about how Webb is an “infrared” telescope (vs. Hubble), which makes me wonder how this can be? We’ve got these amazing gold mirrors, which presumably cannot help but receive light from the whole spectrum, then bounce it to the receiver mechanism.
Which suggests Webb can “see” in any spectrum we want. UV, IR, our human spectrum, etc. So it’s not really that the telescope is limited in any technical sense, it’s just a matter of what we want it to do at a given moment, right?
2 Likes
Somewhat related question: Is it possible to have light without heat? I think the answer is no, but I know we’ve got experts in here far more knowledgeable about this than me.
1 Like
Telescopes must be optimized to operate within specific frequency bands by virtue of what they’re intended to observe, what they’re constructed of, and — sometimes — where the telescope will be located.
- Radio waves are photons just like visible light, but they’re so low in energy that no photon detector yet built can detect them. Therefore they must be treated as waves that induce minute current or voltage changes in an antenna that can be amplified. But this approach doesn’t work once you start to approach the infrared bands — the wavelengths become too short to build functional antennae.
- At the other extreme, x-ray photons are so energetic that they’ll either punch right through the kind of lens or mirror an optical telescope uses without deflecting much or wind up being absorbed by them, so concentric, cylindrical “lenses” are built using dense metal mirrors that ever-so-slightly deflect x-rays to converge on a focus.
- Some substances that are transparent or reflective in the human optical band are actually opaque or have less-than-useful refractive characteristics at other frequencies — and vice versa! The oxygen in the atmosphere is quite good at absorbing ultraviolet radiation, for example. It’s for this reason JWST’s mirrors were plated with gold rather than the typical aluminum optical telescope mirrors are plated with today — gold is a better reflector in the infrared bands JWST is designed to study.
Finally, JWST’s sensors have to be incredibly sensitive to pick up minute variations in low-energy infrared light. In addition to the sunshade and cryocooler that keep them from being swamped by the telescope’s and its mirrors’ own heat, there is an extensive set of adjustable filters in the instruments’ optical paths to prevent anything but infrared frequencies from reaching the sensors.
Short answer — no. Longer answer:
7 Likes