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Light Echoes Solve Mystery of Tycho's Supernova

timothy posted more than 5 years ago | from the bouncy-bouncy dept.

Space 98

Ponca City, We love you writes "Powerful telescopes in Hawaii and Spain are using 'light echoes' from the original supernova explosion that have bounced off dust in the surrounding interstellar clouds to identify the precise type of supernova that Tycho Brahe saw 436 years ago. Although the echoed light from Tycho's supernova is around 20 billion times fainter than the original light observed in 1572, the team took identical images of the sky a few months apart and then digitally subtracted one from the other to find evidence for several sets of light echoes rippling across patches of dust in the northern Milky Way. 'Using light echoes in supernova remnants is time-travelling in a way, in that it allows us to go back hundreds of years to observe the first light from a supernova event. We got to relive a significant historical moment and see it as the famed astronomer Tycho Brahe did hundreds of years ago,' said Tomonori Usuda, of the Subaru Telescope in Hawaii. Tycho's original observations were particularly important as he immediately concluded that the new star, visible even by day, could not be closer than the Moon challenging the Aristotelian view of the cosmos, widely accepted since ancient times, which held that the sky beyond the Moon never changed."

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I want to play. (4, Funny)

suso (153703) | more than 5 years ago | (#26002159)

That is really cool. Like some kind of galactic diff.

Re:I want to play. (0)

SchizoStatic (1413201) | more than 5 years ago | (#26002209)

Lets just hop they don't forget a backslash and fork the display.

Re:I want to play. (0)

Anonymous Coward | more than 5 years ago | (#26002981)

YOU FAIL

Re:I want to play. (0, Offtopic)

morgan_greywolf (835522) | more than 5 years ago | (#26002215)

So what we need is a really a newer, extremely scalable version of patch and then the real fun will start ...

Re:I want to play. (0)

Anonymous Coward | more than 5 years ago | (#26002763)

Watch out for the fruitfucker at the end.

Re:I want to play. (1)

moteyalpha (1228680) | more than 5 years ago | (#26003049)

That seems like it opens up a completely new view of the universe from the past if I understand correctly. They can diff images in all directions and identify unknown supernova events in the past?

Re:I want to play. (0)

Anonymous Coward | more than 5 years ago | (#26004841)

I'm sure it really helps to know where to look. These are very very faint differences. You can't scan the whole sky looking for this. I doubt they could do this on more than a tiny tiny portion. However, there are people scanning the entire sky every few days and comparing images. I remember a Slashdot article on the worlds largest CCD and that's what it was made for. Personally, I'm trilled that it looks like we'll be able to endlessly explore space, even if we physically leave Earth orbit.

Tycho! (1, Funny)

gmccon (179305) | more than 5 years ago | (#26002199)

Did anyone else know that web comics predated the Internet? Tycho Brahe has been keeping it real for hundreds of years!

http://www.penny-arcade.com

wow! (0)

Anonymous Coward | more than 5 years ago | (#26002217)

There was a supernova in that crater on the moon?

Light echoes? (1, Funny)

Tx (96709) | more than 5 years ago | (#26002231)

"Light echoes?" Is there something wrong with the word "reflections" now? Hmm, let me just check my light echo in the mirror..yep, still pretty.

Amazing work though, from my laymans perspective it seems incredible that they can get usable data in this way.

Re:Light echoes? (4, Insightful)

Vellmont (569020) | more than 5 years ago | (#26002311)


Is there something wrong with the word "reflections" now?

In human experience, a reflection is instantaneous, where an echo appears after a period of time. Thus echo is more descriptive to layman (remember them?). You know and I know that a reflection isn't instantaneous, it's just not generally perceptible to our eyes like an echo is perceptible to our ears.

Re:Light echoes? (1)

hcdejong (561314) | more than 5 years ago | (#26012889)

A similar distinction is made in the field of sound and acoustics: reverb vs. echo.

Re:Light echoes? (4, Interesting)

Sockatume (732728) | more than 5 years ago | (#26002357)

"Echoes" evokes the idea that the light from the star first reaches us directly, then a delayed reflection of that light reaches us afterwards. "Reflections" are colloquially assumed to be instantaneous. I think it's a neat bit of semantics, really.

Re:Light echoes? (4, Funny)

Yvan256 (722131) | more than 5 years ago | (#26002559)

HA-ha! You like semantics! /Nelson Muntz

Re:Light echoes? (1)

Gilmoure (18428) | more than 5 years ago | (#26007655)

Eat up Martha!

Re:Light echoes? (1)

severoon (536737) | more than 5 years ago | (#26005333)

Reflections are not instantaneous. (Yes, I'm annoying...but correct.)

Re:Light echoes? (2, Insightful)

osu-neko (2604) | more than 5 years ago | (#26005831)

True. Actually, the real difference between the meaning of the word "reflection" and "echo" lies on in the delay but in the repeat. An echo is a reflection that is perceiving after one has already perceived the same thing the first time. So, although you see the gun fire and a second later here the report, that first hearing of the report is not an echo. But when you then hear the same report reflected off of the wall behind the guy firing the starting pistol, that is an echo. Since we saw the original supernova, then saw the reflection after, the second perception is of an echo. The delay is less important to the distinction than the fact that it's a repeat.

Re:Light echoes? (1)

severoon (536737) | more than 5 years ago | (#26009119)

I understood that echo was a useful term in this context, but I couldn't figure out why it was better than reflection. You, sir, have expressed what I could not quite put my finger on.

You're proof that the int3rpipes is more than just trolls, flamewars, and idgits...thanks!

Re:Light echoes? (1)

Lijemo (740145) | more than 5 years ago | (#26006699)

Thats why he said "are colloquially assumed to be instantaneous" instead of "are instantaneous"

Re:Light echoes? (1)

severoon (536737) | more than 5 years ago | (#26009093)

That's a cop-out. See previous response to my comment for the correct interpretation of the semantics. (btw, osu-neko ftw!)

Why do I say it's a cop-out? Because it can be applied to any bad definition with equally valid results. For instance, I now assert that the poster to whom you refer "is colloquially assumed to be wrong" as support for my response. See? Meaningless.

Re:Light echoes? (2, Interesting)

nschubach (922175) | more than 5 years ago | (#26002629)

That's alright, I'm still trying to figure out which way is 'North' in space... Does North always point to the magnetic pole of Earth even on Mars? Has someone studied the Milky Way and determined that there's a magnetic ring perpendicular to the dish?

Re:Light echoes? (5, Informative)

mrsquid0 (1335303) | more than 5 years ago | (#26002815)

North in the sky is defined to be the point directly above the Earth North Pole of rotation. The northern half of the sky is the part of the sky between the celestial equator and the north celestial pole. For a planet north is defined using the right hand rule of rotation. Curl the fingers of your right hand. That is the direction of the planet's rotation. Stick out your right thumb. That is the direction of the planet's north pole. The same rule applies to Galactic north. Just apply the rotation rule to the Galaxy. Once you get outside the Galaxy supergalactic coordinates are used, which are defined here: http://en.wikipedia.org/wiki/Supergalactic_plane [wikipedia.org] .

Re:Light echoes? (0)

Anonymous Coward | more than 5 years ago | (#26003843)

That's a rather north-centric point of view. [Insert Confederate Flag in ASCII here]

Re:Light echoes? (1)

Chris Burke (6130) | more than 5 years ago | (#26004511)

That's alright, I'm still trying to figure out which way is 'North' in space... Does North always point to the magnetic pole of Earth even on Mars? Has someone studied the Milky Way and determined that there's a magnetic ring perpendicular to the dish?

Don't forget that geographic North and magnetic North aren't the same thing. The concept of North predates any knowledge of magnetism, that just turned out to be a convenient way to figure out which direction North was once the lodestone was discovered (but not perfect, because the magnetic north pole of earth and the geographic north pole are not in the same place, so you need to know that delta when using a compass). The geographic terms north/south were then applied to magnetism, not vice versa.

Re:Light echoes? (0)

Anonymous Coward | more than 5 years ago | (#26005085)

North is not determined by magnetism, even on Earth. North is determined by rotation. Magnetic north and the north rotation axis (north pole) can be very far apart. Even on Earth they are far enough apart to make magnetic navigation tricky.

As others have pointed out, the galaxy also rotates and so has a north. So does Mars. By the way, galactic north is right ascension 12hr:51.4min declination +27deg:07min. The 27 deg declination tells you that earth's north and galactic north aren't the same (it would be 90 deg if they matched). The sun has a north too. Things in the solar system are mostly rotating the same way, so have a similar north (Uranus is significantly different as are many of the smaller objects).

R.I.P. Monument Builders (1)

QuietEarth (1356449) | more than 5 years ago | (#26002291)

R.I.P. Monument Builders

Wikipedia links just for the sake of completeness (5, Informative)

Anonymous Coward | more than 5 years ago | (#26002305)

Here's a link [wikipedia.org] to the supernova in question. Also, here's Brahe [wikipedia.org] himself. Remember that all his observations were naked-eye - pre telescopes.

Re:Wikipedia links just for the sake of completene (1)

UdoKeir (239957) | more than 5 years ago | (#26003313)

Tycho Brahe had a nose [wikipedia.org] made of silver and gold.

And his friend had copper knickers.

Re:Wikipedia links just for the sake of completene (1)

genner (694963) | more than 5 years ago | (#26004847)

Tycho Brahe had a nose [wikipedia.org] made of silver and gold. And his friend had copper knickers.

And he got a moose drunk.

Re:Wikipedia links just for the sake of completene (1)

Kagura (843695) | more than 5 years ago | (#26005161)

And he died from trying to hold in his piss during a drinking game.

Re:Wikipedia links just for the sake of completene (1)

Mr. Slippery (47854) | more than 5 years ago | (#26005739)

And his dying words were, "Let me not seem to have lived in vain". I've always found that haunting. Aren't we all just full of Tycho trivia?

Re:Wikipedia links just for the sake of completene (1)

zapakh (1256518) | more than 5 years ago | (#26005763)

And he died from trying to hold in his piss during a drinking game.

While playing Prince of Persia [penny-arcade.com]

Re:Wikipedia links just for the sake of completene (1)

genner (694963) | more than 5 years ago | (#26006097)

And he died from trying to hold in his piss during a drinking game.

The moose won.

Re:Wikipedia links just for the sake of completene (0)

Anonymous Coward | more than 5 years ago | (#26011563)

This fact is the only thing I actually remember from high school physics.

So, this adds what exactly? (1)

interploy (1387145) | more than 5 years ago | (#26005107)

I'm still trying to figure out what contribution this "discovery" (reenactment?) brings. It's neat they can use this light echo technique to reconstruct a supernova, and it's nice they can now definitively classify Tycho's supernova, but everything else seems to be already known. Even the technique they used to do it doesn't seem new. Is there some new contribution to astronomy here or are they just showing off?

A galactic yardstick? (4, Interesting)

mangu (126918) | more than 5 years ago | (#26002345)

This could be used to determine distances very precisely. If we know when that light was emitted and we know the speed of light, then we can calculate with great precision the distance from the star to the reflecting dust cloud.

Re:A galactic yardstick? (0)

Anonymous Coward | more than 5 years ago | (#26004127)

If we know when that light was emitted and we know the speed of light

We don't know when the light was emitted, only when Tycho saw it.

Re:A galactic yardstick? (2, Insightful)

Timothy Brownawell (627747) | more than 5 years ago | (#26004187)

This could be used to determine distances very precisely. If we know when that light was emitted and we know the speed of light, then we can calculate with great precision the distance from the star to the reflecting dust cloud.

You also have to account for any differences between the earth-star distance and the earth-cloud distance, but it's still the largest ever radar system.

Re:A galactic yardstick? (2, Interesting)

mangu (126918) | more than 5 years ago | (#26004713)

You also have to account for any differences between the earth-star distance and the earth-cloud distance

One could start by assuming that the points which are being illuminated now and have the biggest angular separation from the star are at the same distance from earth as the star. Those points form a circle with a 436 light-year radius. The size of that circle as seen from earth will give you the distance to the star.

I'm assuming that there is enough dust everywhere in space to return a detectable reflection, but even if this isn't true an imperfect circle would still give us usable data. At the distance that star is, about 7500 light-years, this would probably more accurate than other methods.

Supernova 1987A [wikipedia.org] has had its distance measured by a similar method, look in this picture [wikimedia.org] how the reflections appear.

Re:A galactic yardstick? (0)

jollyreaper (513215) | more than 5 years ago | (#26006637)

You also have to account for any differences between the earth-star distance and the earth-cloud distance, but it's still the largest ever radar system.

If they're light echoes, shouldn't it be sonar?

Re:A galactic yardstick? (1)

gyrogeerloose (849181) | more than 5 years ago | (#26007593)

If they're light echoes, shouldn't it be sonar?

LIDAR, actually.

Re:A galactic yardstick? (2, Informative)

halcyon1234 (834388) | more than 5 years ago | (#26005081)

Although... if we know when that light was emitted, then we know the distance to the supernova already. There's four pieces of information that could be known. If we know two of them, we can map out the Earth/Supernova/Cloud system:

  1. The distance from Earth to the Supernova at the time of the supernova event (equal to the time it took for light from the supernova to reach Earth)
  2. The distance from the supernova to the reflecting cloud (equal to the time it took for the light from the supernova to reach the cloud)
  3. The distance from the reflecting cloud to Earth (equal to the time it took for the reflected light to travel from the cloud to Earth)
  4. The angle between the cloud and the supernova, with earth at the origin (projected onto two dimensions of your choice, for convenience)
    1. We know 1 is about 7500 light years. I can only presume that the smart brains behind the telescopes can tell determine 3 from looking at the cloud. However, if they can already position the cloud, then you don't need to know 2, you can work it out even without the reflected light

      The hard part, I would assume, would be doing the math on not where everything is, but where everything was when the light hit, and adjusting accordingly.

Re:A galactic yardstick? (0)

Anonymous Coward | more than 5 years ago | (#26015185)

the phrase you want is standard candle, and not really.

A million bright ambassadors of morning? (-1, Redundant)

yellowstone (62484) | more than 5 years ago | (#26002403)

How are "light echoes" different from "reflections"?

Re:A million bright ambassadors of morning? (0)

Anonymous Coward | more than 5 years ago | (#26007761)

I guess the same way that "sound echoes" are different from "reflections", or that "radar echoes" are different from "reflections", etc. Perceive an event once, it may be a reflection. Perceive the same event twice (or more), it is an echo.

Reverse Ray Tracing (5, Funny)

Doc Ruby (173196) | more than 5 years ago | (#26002419)

When can we point our telescopes at an object hundreds or thousands of lightyears distant, and pick up the light reflected back at us that previously traveled from Earth to that object, then reassemble it into images? Images of the Earth's past, twice as old as the lightyear distance of the object?

We could look at an object 1000 lightyears distant for reflections of Jesus being crucified. Search among objects 250-600 lightyears distant for reflections of people arriving in the "Americas" on ships before Columbus. 176ly distant objects could show us images of Newton getting hit by a falling apple.

Finally a use for the combined computing power of all Earth's computers.

Re:Reverse Ray Tracing (4, Informative)

glaswegian (803339) | more than 5 years ago | (#26002731)

We would need monumentally large telescopes for this. The largest optical telescope on earth, the Keck, has a diameter of 10m. Using the Rayleigh Criterion [wikipedia.org] , we can calculate the minimum resolvable detail at a given distance. For example, we can resolve details on the surface of the moon (in the visible) that are around ~20 meters across. If you want to resolve an apple falling on somebodies head you need ~10 cm resolution. So to see this happening on the moon we would need a telescope with a primary mirror ~ 2.6 km across. To see the same thing echoed back from a dust cloud near the closest star to our sun (4 ly * 2), you would need a telescope with a primary ~ 7e+10 m across or around half the distance between the earth and the sun. Not to mention that the signal would be very weak and completely lost in noise.

Re:Reverse Ray Tracing (1)

frieko (855745) | more than 5 years ago | (#26003629)

This wouldn't do anything to improve SNR, but two ordinary telescopes 7e+10 m apart have the same resolving power as one giant one.

Re:Reverse Ray Tracing (4, Interesting)

Doc Ruby (173196) | more than 5 years ago | (#26003825)

A telescope array [wikipedia.org] acting as an interferometer doesn't need to be a single large sensor like that. We can orbit the array with separations of 1E13, just beyond Neptune. That would give us resolution of something like 5.8E-20 arcseconds. The radius of that regular polygon with 10cm sides is about 7E21m, or about 740,000 light years. Which would show light that left Earth about 1.48 million years ago. Orbital arrays much closer to Earth are sufficient for looking for apples only 175ly away.

The signal to noise is of course extremely high ("astronomical"). That's why I mentioned the combined computing power of all the world's computers. We're gonna need a bigger boat, but that's a good sea to sail her on, to catch this shark :).

Re:Reverse Ray Tracing (1)

Kagura (843695) | more than 5 years ago | (#26006027)

Can somebody please explain why this is? I understand the difference between total collecting area and actual resolving power, but I'm missing something fundamental. It doesn't seem like two telescopes linked by interferometry should increase the resolution just because they are separated by a large distance. To me, I can only imagine an increase in resolution because the total collecting area is increased, but not due to their separation.

My question is, why does separating two telescopes by distance greatly increase resolution? I can also imagine an extreme case where the two telescopes are separated by such distance that they are viewing different sides of the object.

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26006477)

You can look into aperature synthesis [wikipedia.org] , which is the technique at work.

Re:Reverse Ray Tracing (1)

Kagura (843695) | more than 5 years ago | (#26006647)

Thanks, but I read the page and a couple others, but still didn't get my answer. :( I don't see how separating two telescopes and connecting them by interferometry increases the resolution so dramatically.

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26007303)

You're getting double the information by using two telescopes. Most of the info is redundant. But there is phase info, available to the "phased array", in what you're getting. The interferometry is the method of extracting the phase info. The phase info isn't redundant between the two telescopes. So that extra info is an increase over the single telescope's. The extra info is the increased resolution.

Re:Reverse Ray Tracing (2, Insightful)

Urkki (668283) | more than 5 years ago | (#26007223)

It's not just computing power. We'd actually need to catch enough reflected photons that originated from the Earth, so we'd have anything at all to process.

I think it would be a problem even if there was no other light except what we want to observe, ie. there would be no external noise.

Also, the "mirror" isn't a flat plane, so we'd get a bunch of "Earth photons" that originatead at different times, reflected at different times, and then arrive at our telescope at the same time.

To get anything useful, we'd need to have a very sharp focus, and then move the focus at the speed of light, so we'd collect photons that originated at the same time, but reflected at different times.

So sharpness of focus would determine temporal resolution. If we'd want to catch an apple falling, we'd need temporal resolution of maybe 1/10th of a second (and that would still be quite a blurr), so focus would have to be 1/10th of a light second... I don't know that much about optics, but achieving that at a distance of hundreds of light years would be quite a feat too... Will a telescope array help with achieving a sharp focus at a great distance?

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26007463)

The flatness of the surface isn't really a problem, because the photons that arrived a little later (by speed of light, the distance of the "roughness") are going to be extremely similar to the ones that arrived at the time of the first photons reaching the closer parts of the roughness. In fact what helps us is our tolerance of a somewhat soft focus. Since our resolution is 10cm, which light travels in 3.33564095E-10 seconds, our probably much longer exposure (to collect photons) means our focus is not going to be precise anyway.

The main problem, bigger than reconstructing the image that didn't pass through a collimating (projecting) lens (though the atmosphere's curvature might give us something to work with, however fuzzy at the "boundary" with vacuum), is indeed all the other light on the reflecting object. We could probably filter that by spectrographic filters, though we'd be guessing at the precise spectrum of the ancient light of the Sun.

This whole thing would be quite a feat, at every step. But it does seem to be within physical limits. So given enough time to work on it, "we" might eventually pull it off.

It will have been fun in the future to watch us type these responses back here (and now). Just sit closer to the window, and you'll be famous for it someday!

Re:Reverse Ray Tracing (1)

jagdish (981925) | more than 5 years ago | (#26010257)

Its funny how in this economic climate the meanings of the words economical and astronomical have interchanged.

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26010851)

Inverting the ratio by calling it "high" has a way of doing that :). Nice catch.

Re:Reverse Ray Tracing (1)

geekoid (135745) | more than 5 years ago | (#26008853)

Dude,
Just put the image in photoshop and zoom way in~ duh I see t on TV all the time

Re:Reverse Ray Tracing (1)

witherstaff (713820) | more than 5 years ago | (#26005021)

Jack McDevitt had a similar idea in one of his books. The protagonist is a historian's assistant. One of the ideas was to use faster than light travel to intercept old radio and video broadcasts to recover some history. I believer it was mentioned in Seeker [scifi.com] but I may be wrong. The characters got sidetracked by something else so never got past the idea stage.

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26005759)

I didn't know about McDevitt's version of this idea. I thought of it when thinking through "faster than light travel" applications, when I realized that reflected light "bends space" back to the source, which is effectively time travel. I was helping build a digital camera out of a lot of cutting edge DSP for noise reduction and feature enhancement, including some efforts at reversing the effects of air turbulence confusing light paths to the sensor. It occurred to me that similar processing, but more advanced, could "clean up" the reflections of Earth from distant objects. Pluto is frozen and kind of "shiny", and by extension so are other distant objects. The computation might be far too vast for our current computing methods, even if all of our computers were dedicated to it. But quantum computing methods, especially in later generations (harnessing all the subatomic particles, not just the "big" ones and their simplest quantum states), could deliver the power.

It's certainly worth thinking about. Because if it worked, the value would be unprecedented. Age old questions, some religious (various miracles), some political (conduct of ancient original conflicts), some scientific (video of ancient ecologies), and others of wide impact, could be settled with visual evidence understandable to anyone (if sufficiently reconstructed). And if we're ever going to do it, we're going to have to think about it a lot before we get there.

If only we could reverse the technique, and peer at very close objects to see the future, we might learn quicker how to look at the past :).

Re:Reverse Ray Tracing (2, Interesting)

AlejoHausner (1047558) | more than 5 years ago | (#26010299)

This would definitely not work. There is no imaging (no lens, or pinhole) at work. What you are proposing is analogous to sitting in a dark room with white walls with the television on: you will see areas of color on the wall, but you will be unable to deduce from these reflections what the picture on the TV looks like (beyond getting the average color of the TV picture). Of course, if the wall were a mirror, you could do it, but walls are diffuse reflectors, which means that, at each point on the wall, any light arriving is scattered into a 180-degree hemisphere of directions. The light reaching your eye from any point on the wall comes from the whole TV screen. You can't easily undo what is, effectively, a massive blurring operation.

To make matters worse, room walls are white, and reflect light back and forth to each other, so a large fraction of the light you see on the wall has already bounced off one or more other walls. Thus it's undergone several blurring passes.

This latter inter-reflection problem will, of course, happen in space too. There's lots of nebula to scatter light.

And, what's worse, we don't know exactly where those nebular are, at least not precisely enough to get the data needed to undo the blurring, assuming that were at all feasible.

Alejo

Re:Reverse Ray Tracing (1)

Doc Ruby (173196) | more than 5 years ago | (#26010879)

That's where the reverse ray tracing comes in :).

There are probably plenty of distant objects with little to no intervening matter. And then there's probably distant objects that have intervening matter that collimates light, either optically or gravitationally.

Tycho Brahe - Amazing (4, Insightful)

Aladrin (926209) | more than 5 years ago | (#26002429)

I'm amazed that he was able to observe that and figure out that the common concept of the sky was wrong at the time. I can't imagine how much thought must have gone into something like that.

Re:Tycho Brahe - Amazing (3, Informative)

Aliks (530618) | more than 5 years ago | (#26002713)

Well he had already done a lot of work on parallax measurements for astronomical objects. So when the supernova appeared, and showed no parallax against the moon . . . he was on pretty firm ground stating that the moon was closer to earth than the supernova.

More details in Wikipedia.

Re:Tycho Brahe - Amazing (0, Offtopic)

dkleinsc (563838) | more than 5 years ago | (#26002955)

And even more amazing is that a guy that smart didn't know when to empty his bladder.

This has been a message from the Tasteless Jokes Department.

Re:Tycho Brahe - Amazing (0)

Anonymous Coward | more than 5 years ago | (#26006999)

Wikipedia suggests that this may be a myth, and Brahe was in fact poisoned with mercury.

I dare the Mythbusters to show that you can keep it in you so long that your bladder ruptures.

Alex

Re:Tycho Brahe - Amazing (1)

radu.stanca (857153) | more than 5 years ago | (#26003045)

Not actually true, Tycho Brahe's model of the solar system was very similar(geometrically) to Ptolemy(earth in the center) and Copernicus(sun in the center). He put the earth in the center, the sun and the moon were orbiting around the earh while the other planets where orbiting around the sun.

The real breakthrough came from Johannes Kepler( who was working with Brahe and later on was using Brahe's observations) who went away from using circular orbits, and to a certain extent discovering gravity. You can read more in his book Astronomia Nova, I recomend it to anyone.

Re:Tycho Brahe - Amazing (1)

Aladrin (926209) | more than 5 years ago | (#26005187)

The 'common concept' I refer to is that the night sky's background is static, as was mentioned in the summary. I'd have been even more impressed if he'd figured out the Earth wasn't the center of the universe at the same time.

Re:Tycho Brahe - Amazing (2, Insightful)

lawpoop (604919) | more than 5 years ago | (#26010567)

It is laudable, but I wonder how much doubt there was going on at the time. For instance, the Greeks knew that the Earth was round, but there was common conception that the Earth was flat -- I'm not talking about what educated people thought, but what the commoners thought. European scholars studied classical literature ( back then it was just "literature" I guess ), and they were exposed to ideas from the Greeks and the Muslims, who helped transmit the Greek texts. So they got exposed to a lot of different ideas.

The official line of the church was that the heavens never changed and were perfect, and if you wanted to be in the good graces of the church, which was a good idea to a lot of people, they towed the line. Of course, to the common person, the sky was a round dome, because that's what it looks like, and that's what the priest tells him. But I think that the educated class might have been more open-minded.

Anywho I have a friend who claims that our perception of the universe is wrong -- we're basically looking at a big optical illusion that also affects gravity somehow. He doesn't claim to know what it should really look like, but he says what we are seeing is an optical illusion. I can kinda see his point -- all the instruments we have are earth based, and if there's some uniform membrane or something around the solar system, how could we tell? I don't know enough to prove him wrong, so whatever.

Doubting Thomas (2, Funny)

cidhawk (732233) | more than 5 years ago | (#26002553)

Tycho: I saw a light in the sky that looks like an exploding star.
Scientific community: We don't believe you until we can see it ourselves. Neh!

Re:Doubting Thomas (2, Informative)

mrsquid0 (1335303) | more than 5 years ago | (#26002823)

Actually, the scientific community of the time (such that it was) was mostly convinced by Tycho's observations.

Humankinds' endless fascination with the sky... (2, Insightful)

Tastecicles (1153671) | more than 5 years ago | (#26002683)

...continues to bring surprises like this. I'm just wondering if this is the same method we astronomers use to detect local masses such as transneptunian planets (or "Plutoids", if you will) or asteroids or -gulp!- Near Earth Objects such as the Saturn V Stage discovered and misidentified as a natural coorbiting body a couple years ago? Could light ripples be detected and identified on a pair of plates of the same patch of sky taken a year apart?

20 billion times fainter? (1)

ScentCone (795499) | more than 5 years ago | (#26002733)

I hate those expressions! That implies that the original light was faint. But faint compared to what? Why not just say that it was 1/x-th the brightness of the original event's visible light? The echos/reflections are relative to the original, in terms of what makes the story interesting. Both the original event and the reflections are found on some hard scale of luminosity, but that's not referenced... so why the awkward, un-anchored, and thus meaningless reference? Grrrr. 20 billion times fainter than the original... which was what? Half as bright as the full moon? Brighter than the sun? Brighter than an ascending science journalist or summary writer?

Re:20 billion times fainter? (4, Interesting)

TheThiefMaster (992038) | more than 5 years ago | (#26003095)

xxx times less than yyy == yyy/xxx.
It's common language these days, learn it!

Re:20 billion times fainter? (1)

IndustrialComplex (975015) | more than 5 years ago | (#26003433)

xxx times less than yyy == yyy/xxx.
It's common language these days, learn it!

He wasn't asking how to express it, he was asking them to include YYY if you are going to call something XXX times fainter than YYY so that he has some clue as to the starting point.

This object is 100 times lighter than object B. That doesn't tell you much since object B could be a gnat, a basketball, or a galaxy.

Re:20 billion times fainter? (1)

TheThiefMaster (992038) | more than 5 years ago | (#26004237)

I got a +5 already, so it doesn't matter :) /joking

But seriously, if something is 20 billion times fainter it's going to be barely visible, regardless of how bright the original is.

It's also more impressive journalism to use "20 billion times fainter" than "1.3 candles" or some other actual measurement.

Re:20 billion times fainter? (2, Interesting)

CrimsonAvenger (580665) | more than 5 years ago | (#26005125)

But seriously, if something is 20 billion times fainter it's going to be barely visible, regardless of how bright the original is.

Our sun is ~20 billion times fainter than it will be when it supernovas. And seems to be bright enough to light up the world nicely. OP is right, it would be nice to know how bright the original was.

Re:20 billion times fainter? (1)

Tastecicles (1153671) | more than 5 years ago | (#26007111)

sorry, pal, Sol is just too small to supernova. It's short by about 1.4 solar masses. What'll likely happen is it'll burn out of hydrogen, start burning helium and contract, then when it starts to burn heavier elements (lithium, beryllium, through carbon, nitrogen, oxygen...) the outer shell of helium will cool and expand out to the orbit of Venus and possibly Earth. By this time the core'll be burning even heavier elements, but due to the size of the sun it won't even reach the iron cycle - the photosphere'll just keep expanding and cooling until it finally dissipates leaving a cooling cinder - what's left of the sun - to drift through the Sagittarius Arm of the Milky Way towing along a charred and barren Earth. Another few million years and Sol will just be a lump of cold nuclear waste.

Re:20 billion times fainter? (2, Funny)

ScentCone (795499) | more than 5 years ago | (#26007815)

Another few million years and Sol will just be a lump of cold nuclear waste.

Hey, don't sugar-coat it, OK?

Re:20 billion times fainter? (0)

Anonymous Coward | more than 5 years ago | (#26003327)

My issue with those expressions is that "20 billion times" means bigger, but "fainter" means smaller. How can something be bigger smaller?

Re:20 billion times fainter? (1)

Quirkz (1206400) | more than 5 years ago | (#26003889)

Well, the article does say the original object was "brighter than Venus" so that's a start. Also, considering these were naked eye observations, it's not even possible to have a precise brightness value for the original. That of course means the 20 billion number probably is more of a guess than a precise number, but I wouldn't say it's completely useless to mention here.

Re:20 billion times fainter? (1)

nedlohs (1335013) | more than 5 years ago | (#26006191)

The article that line is a link to (and that the line was extracted from) states (in the first paragraph no less): "as bright as the planet Venus".

Which considering the time frame of the original observation is as precise as you are going to get.

I'm going to take a punt that 99.9% of people get a more accurate idea from "as bright as the planet Venus" (provided they know which dot in the night sky you are referring to by that name) than "an apparent magnitude of -4.5".

Re:20 billion times fainter? (1)

kayditty (641006) | more than 5 years ago | (#26012237)

-4.5 wouldn't put it brighter than Venus at its most brilliant. it probably was between there and -10, though, or he would've said it was brighter than the moon, you'd imagine.

Re:20 billion times fainter? (1)

nedlohs (1335013) | more than 5 years ago | (#26025413)

"as bright as" != "brighter".

And yes, I'm talking about what the article says not what Tycho said...

Re:20 billion times fainter? (1)

kayditty (641006) | more than 5 years ago | (#26056293)

I read the article, asshole. this page [timesonline.co.uk] said, and I quote, "In the constellation of Cassiopeia, he clearly made out what appeared to be an entirely new star, brighter even than Venus, that had not been there before."
I'm sorry if that eluded you.

go to the bathroom, genius (0)

Anonymous Coward | more than 5 years ago | (#26003295)

too bad Tycho was too stupid to get to the bathroom on time, though...

Tycho Brahe (0, Troll)

maillemaker (924053) | more than 5 years ago | (#26003699)

Couldn't hold his pee pee!

Re:Tycho Brahe (0)

Anonymous Coward | more than 5 years ago | (#26005009)

Couldn't hold his pee pee!

He died of mercury poisoning [wikipedia.org] . The bladder story was invented by the person believed to be his murderer.

He DID know how to party! (1)

avandesande (143899) | more than 5 years ago | (#26005879)

Tycho's elk and dwarf
Tycho was said to own one percent of the entire wealth of Denmark at one point in the 1580s and he often held large social gatherings in his castle. He kept a dwarf named Jepp (whom Tycho believed to be clairvoyant) as a court jester who sat under the table during dinner. Pierre Gassendi wrote[6] that Tycho also had a tame elk, and that his mentor the Landgrave Wilhelm of Hesse-Kassel (Hesse-Cassel) asked whether there was an animal faster than a deer. Tycho replied, writing that there was none, but he could send his tame elk. When Wilhelm replied he would accept one in exchange for a horse, Tycho replied with the sad news that the elk had just died on a visit to entertain a nobleman at Landskrona. Apparently during dinner[9] the elk had drunk a lot of beer, fallen down the stairs, and died.[10][6]

fr0st pist (-1, Troll)

Anonymous Coward | more than 5 years ago | (#26006145)

Let's keep to alrEady dead. It is A dead man walking. CorPorate I don't want to see... The number

More substantial link (2, Interesting)

AlejoHausner (1047558) | more than 5 years ago | (#26006241)

Here is a link to an article by one of the researchers involved in this work

http://www.naoj.org/Pressrelease/2008/12/03/index.html [naoj.org]

As the article suggests, the biggest benefit of using light echoes is that the SPECTRUM of the original supernova can be obtained. In other words, while today we mostly see the direct-path light emitted by the supernova's gas remnant, light echoes let us see all the wavelengths of the light emitted at the time of the explosion.

Alejo

Re:More substantial link (1)

Tastecicles (1153671) | more than 5 years ago | (#26007021)

wow... that brings up a whole mess of possibilities! For instance, we can tell from the amount of light reflected and the intensity of reflection, what a local mass is made of (by the absorption spectrum) and extrapolate how dense it is. In the same manner, we can tell what a star is made of (hydrogen and helium, usually, with a mess of other elements up to iron - after which nuclear reactions are endothermic) by its emission spectrum, and if we can be sure that these light echoes are of the same wavelengths as the original emission from the explosion, we could conceivably tell the composition of the star and even how big it was moments before it exploded. This might not sound very exciting to the Layman, but believe me when I tell you, it'd cement current theories as to what a star has to do to explode...

Re:More substantial link (1)

AlejoHausner (1047558) | more than 5 years ago | (#26007159)

That's an interesting idea. You could hypothetically look at the light emitted by the pre-supernova star, as it was reflected off a nebula. The trouble is that, before the explosion, the star isn't especially bright (well, a heck of a lot dimmer than a supernova). Hence the reflected light wouldn't stand out very much, and I doubt you could subtract out the light on the nebula due to other sources. But you might catch the rising part of the supernova's light curve.

Alejo

Tycho Brahe? (1)

bluefoxlucid (723572) | more than 5 years ago | (#26006441)

Was he playing D&D 436 years ago? There was no XBox back then o_O

By Neruos (1, Insightful)

Anonymous Coward | more than 5 years ago | (#26006963)

all these high powered telescopes that can 'supposely' see 10000000000x millions of light years away and yet there are no close up's of the moon, the flag on the moon, the machines left on the moon or any other human impact images of the moon from multiple sources across the world. No images exist except those from the 1969.

why? Think about it.

Re:By Neruos (1)

Tastecicles (1153671) | more than 5 years ago | (#26007187)

you look at the moon through a small telescope (don't do this on a full moon, you'll burn your retinas!). Oh wait, that prenthesis is the whole point of the exercise. Deep space telescopes such as Hubble are insanely photosensitive. They can't even use HST to look at Earth's surface, it'll overload the CCD sensors. Light reflected by the lunar surface is unfiltered raw sunlight. You'd be better off using interferometry to look for your landing sites... it's better for your eyes and better for your cameras...

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