Name: 洛基太空火山--60個符號。 (Loki the Space Volcano - Sixty Symbols)
Uploaded: 2021-01-14T10:31:59.000Z
Duration: 7 min 57 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

To be honest, it looks like a mistake that looks like it's got a water stain on it or something.

So, in fact, the black part was taken by the Voyager space probe as it was wondering past the solar system as it went past.

This little bit of Io is a tiny volcano on either.

In fact, this is the most active volcano in the solar system.

It was an image that was taken recently off that volcano from the ground.

And that's the amazing thing that things that a few years ago we could only even hope to see you by actually going and seeing them, you know, sending a space probe on actually going up close to have a look.

We now have the quality of images we can now take with telescopes on the ground means that you can actually see them from the ground.

The scale here we're talking about, like a few 100 kilometers across.

It's on you know a fairly small scale of things on there, too.

Clearly these two bright patches and this is kind of looks like a horse.

Yeah, but it's thought that one of them is actually the erupting volcano itself.

And the other is that this is just his massive lava lake that forms.

And you can actually, when you have these lava lakes, just that you get the same kind of phenomenon on Earth, they tend to crossed over, and then the cross sinks and suddenly you see the lover again and so on.

So what we think's happening here is that you actually this one of the faces where you can see this massive lava lakes around in the volcano.

This is in the sort of near to mid infrared, so it's a few microns wavelengths beyond the visible wavelengths into the infrared part of the spectrum.

Which is why volcano sharp Very well, because they're hot on that.

So these kind of wavelengths, the infrared is a very good place to look.

You're really seeing that bright, hot ambition.

It's an amazing thing with this idea that actually weaken, take sensible pictures of geological phenomena on a moon of Jupiter from the ground is an amazing that the sharpness of the image you need to be able to pick out this kind of detail on something so tiny so far away is absolutely outstanding.

There's a couple of limitations to how sharp and image you could take from the ground.

In fact, we talked about this a few times before.

One is that the Earth's atmosphere messes things up, and so, actually that blurs the images so you can take very sharp images because of the earth's atmosphere.

The other Is this a fundamental limit that basically says that the sharpness of your image is dictated by the size of your telescope and the bigger you make a telescope?

Sharpe of the images you could make on what this new image has done is basically sort of solve both of those problems in the sense that it uses some very sophisticated techniques to get out.

Both get rid of the effects of the atmosphere and to deal with this limitation off how sharp and image you can take with a finite size of telescope Okay, so I have another picture for you.

It's a thing called the Large Binocular Telescope or the Lbgt.

It's on Mount Graham in Arizona, joint venture by several countries that run this telescope.

Each of these is an 8.5 meter diameter mirror to give you a sense of the scale of this thing.

That these two very big telescope was a bit unusual about it is that they're no independent telescopes, actually, both points in the same direction, so they actually you can combine the light from the two on.

You can just use that combined like to look at fame to things because you got more collecting area.

So you have seen many things, but the need to trick here is actually you can combine the light from the two in a coherent fashion, which, in terms of this sharpness limit this diffraction limit for a telescope means that effectively, you've got a single telescope that's kind of the the distance between the two of them, rather than the diameter of each, each one individually.

So the effective diameter of the two when they're working together, I think it's about 22 or 23 meters.

Figuring out the angular resolution of thes image is a very, very sharp image.

Very small, angular scales is about 32 million arc seconds.

And I was doing trying to figure out something that puts that into perspective in perspective.

You could see how many fingers I was holding up for my hand if I was standing on 100 kilometers away from you 60 miles away from you, using an image of that sharpness.

So it's really is picking out incredibly fine detail because of this very high, angular resolution you have with this technique.

Professor, if you stood 60 miles away from the telescope in Arizona and I swung around and pointed it, I suspect I probably don't emit brightly enough in the infrared for it to actually be able to record my admission.

But certainly in terms of the resolution of the images, yes, it will be able to tell that, but I would have to be glowing fairly brightly in the afraid for that to work, so that's acting like one mirror.

But it's pretty clear to May there's some pretty Nicole's in that mirror.

There's a huge gap in between and above, and like like that's like a mirror with most of the mirror missing, too.

Yep, and it's actually it's worse than that because it's if you think about it, it's actually bigger in this direction that is in this direction, which means in terms of the sharpness of the images you get, the images are much sharper in the horizontal direction.

They are in the vertical direction, and you've got all these gaps and so on.

So there's a couple of again a couple of tricks you can play, which is, if you think about it as you trace an object if you think about a kind of an extended object.

So here I am with my telescope looking this way, and it's following this extended object when an object what happens to it is as time goes on as the earth rotated will rise and then it'll set again.

And if you look at the direction of my hand, you can see that actually, the story here my hand is pointing kind of more or less upwards that it becomes horizontal, Then it points downwards.

And so, actually, at different times, I can use this extra resolution.

The telescope has in the horizontal direction to tell me about different aspect of this object because it's it's orientation is changing as it tracks across the sky.

And so, by combining images that you've taken a different times as an object tracks across the sky, you can actually use that extra resolution in all directions to get a sharp an image which is sharp in all aspects, rather than being squashed one way and very sharp in one direction and blurred in the other direction.

You could combine all those images together to create a single image of the object, which is a sharp, as if you had a a single telescope, effectively kind of this kind of size and round.

Why don't they make every telescope like that?

Because it's actually hard to get this to work.

This is a you know, it's a very sophisticated technique.

This is probably the best image I've ever seen taken with this kind of technique.

You do have this problem that you can't just take a snapshot.

You do have to combine this whole series of images together, and then you go to duel this fancy processing The object needs to be relatively bright, so you can do these kind of techniques on it.

There are still real advantages of having a single big telescope.

But what this telescope is really giving us is kind of a foretaste of the sorts of things we're gonna be able to do when that next generation of big telescopes comes along.

Because already it's getting images of kind of the sharpness we will get with a single, very large telescope.

I've seen some pretty impressive images off I taken by space probes that went toe.

I I mean, surely that's that's where it's that you can't you can't and you can see the quality of the image we're getting.

You know where you're seeing things 100 kilometers across when you actually got your space for going there you can see something which is one kilometer across, or maybe in 100 meters across.

The downside is it takes you a long time to get there.

He cost you rather a lot to get their space probes incredibly expensive.

We have ignition and lift off of Atlantis on the Galileo spacecraft bound for Jupiter and Sunnyvale.

Flight director has just confirmed the successful deploy of the inertial upper stage and Galileo.

It's an answer that flight controllers in the world and typically if it's a fly by mission, you get one shot of having a look at things and then you're gone.

We can actually monitor this volcano night after night, year after year to see, actually, How's that structure changing?

How is this most active volcano in the entire solar system erupting?

If I gave you a big whack of money or Bill Gates gave you a big bag of money until it's purely your choice?

Mark, do you want to build a space telescope or a huge array of these things?