These supernova follow a reasonably well-known light curve, and so by measuring its apparent brightness and knowing what its actual brightness is, you can get a rough cut at the distance.
If it was in our galaxy, it would be MUCH brighter.
I think you've misunderstood the program slightly.
Gamma Ray Bursts are seen across the sky at a rate of a couple of bursts per day, with the current detection limits. The latest theory is that they are the last stages of a binary pulsar (two neutron stars orbiting each other) spiralling together and just before they coalesce, an intense, beamed burst of gamma rays is emitted from this system. We are seeing the bursts from many millions/billions of light years away, and for us to be detecting them over that distance, the implication is that the energy release is awesome, to say the least.
Any star system in the galaxy in the GRB's beam path is immediately sterilised. It doesn't have to be *our* star, we just have to be in the way of a burster's beam. Thankfully we don't see any binary pulsar systems in our own galaxy that look close to doing this soon.
This is used to great effect in Greg Egan's "Diaspora" which details what happens to the Earth when a GRB goes off nearby, and Stpehen Baxter uses the idea of many GRB's sterilising the galaxy every 100 million years to explain the Fermi Paradox in his great series: "Manifold: Time"
Having used LyX for a couple of years, I've found it to be incredibly useful for many simple documents and poster displays. The one gripe that I have, though, is with the conversion to PDFs when you have embedded postscript files, or the page is a non-standard size. The PDF it produces can be very wonky, and/or suffer from the dreaded "embedded bitmapped font" syndrome which makes PDFs about 10 times larger and look shit on a computer screen.
The good news is that the LyX team are very aware of these kinds of problems and they are very enthusiastic with helping you out, even with simple questions. It's everything you hoped an enthusiastic Linux community would be.
> My biggest problem with modern science (physics
> and astrophysics in particular) is this truly
> inane method of making "conjectural"
> observations...that is, assuming that and
> unobservable activity has been proven simply
> because something observable has occurred.
OK. We know from the distribution of light and the measured rotational velocities of most galaxies we can see that they seem to be embedded in a large halo of gravitating mass. This has been measured and confirmed many, many times over that past 40 years.
When you add up the total amount of emitted light from a galaxy, you can get an estimate of it's mass and that turns out to be about 10**12 solar masses, say.
Looking and the dynamic motion of the galaxy using the Doppler shift of spectral lines from stars in the galaxy, you calculate that the required amount of mass for the galactic motion is roughly 100 TIMES the amount you count up by counting stars/gas/glowing stuff alone.
1) Maybe this 'dark' matter is not being illuminated by stars? No - do the calculations and it turns out that this stuff would be detectable. Instead, we see nothing. So, we can rule out baryonic (protons, electrons, photons) matter. Therefore, it has mass but it doesn't interact with baryonic matter - it is only gravitationally coupled with baryonic matter.
2) Maybe it is condensed into cool stars that we can't see? Again, no luck there. Really dim stars are hard to detect, but over the past 5 years, enough have been detected to make a guess as to whether dark matter is this form. There isn't.
So, we still have no clear idea what dark matter is made up of, but a lot of ideas that we can test. I'll admit that it's incredible, but believe me, there's a lot of evidence for dark matter. Alternative hypotheses, such as modified long-range forces have been tried out and don't work (and no, it's a separate issue from non-zero lambda cosmologies!) so we are back into the 'small, energetic, low mass subatomic particle' game.
What we are NOT doing is inventing dark matter, as you imply. We tend to leave it to the mystics.
If you're interested in the more detailed reasons why, please feel free to contact me.
The problem comes in formation. Binaries do not coalesce to form larger mass black holes (it's a problem of getting rid of the huge angular momentum storead as the stars orbit each other), except possibly as binary black holes which take many mega-years to spiral into each other via gravitational radiation loss. 14 solar masses is also larger than the sum of masses of most binary systems, and those systems which *do* have large masses don't merge for dynamical reasons (mostly the AM problem above).
The interest is that there's no clear formation mechanism for these medium-sized black holes.
P.S. If a neutrino is chargeless, how do you "fire" one at something?
How about a beam of relativistic charged particles that decay and release neutrinos as a byproduct? Relativistic beaming means most neutrinos in our rest frame are being beamed in the direction of propagation.
There's been a lot of talk at coffee mornings in our astronomy department about "press release publishing", where scientific results that have not passed through peer review get column inches in the American broadsheet newspapers. Although new results are exciting and the urge to shout them from the mountaintop is strong, it's a very dangerous trend.
The majority of American science departments are trying to crack down on this, but I think it's only a matter of time before we get another "Cold fusion" fiasco in one of the sciences again, and that can't be good for anyone in the research fields concerned.
My parents are both teachers in a local British boys school, and they both think computers are the biggest waste of resources possible.
Both work in the 'Information Resource Centre' (i.e. the library) where sixteen PCs are networked together as an 'information resource', according to President Tony Blair's grand new view of 'A computer on every child's desk' (hmmm, reminds me of another megalomaniac....). The theory is that the kids learn about the computers and how to use them in order to prepare them for the real world which (apparently) has computers everywhere. The truth of the matter is that the boys download tons of porn and set it up to appear as backgrounds on other users' accounts. The school ran out of money for a competent sysadmin and the current poor soul doesn't know how to manage his own arse, never mind the pitted ingenuity of dozens of horny teenagers.
Even as an 'information resource' (gak - horrible phrase!) the Web is basically shit for any reasonably detailed material. Yes it's fun to surf, but when I *really* need to check facts, I go off to a library and get it out of a dead tree tome. Books are critically reviewed, the web is not. GIGO en masse, and most importantly:
1 computer == 50 books.
Palms will only be used for playing games/gossiping/switching the TV on and off when the lesson gets boring, and there are always times when playing *any* game, no matter how crappy and pixellated, will be preferable to listening to a lesson.
I don't think he would've been too pleased to be called a big bang theorist - he was an advocate of the steady state theory, and came up with the name 'big bang' to make fun of the then opposing cosmological theory. Ironically, the name 'big bang' stuck.
I was a graduate student at the IoA in Cambridge (which Fred Hoyle founded), and I met him a couple of times. He was still keeping up with contemporary research and had a few great stories to tell. A very clever man, and sharp as a tack.
His sci-fi books feature (unsuprisingly) a lot of astronomy - I just read "The Black Cloud" and it's a pretty good read, I'd recommend it to anyone interested.
Their funding has been going for at least 10 years, and their technique is as accurate as it sounds. Iodine absorption spectroscopy *is* as accurate as the the numbers claim (about 3m/s at the last look).
The phrase "By focusing extremely precise measuring techniques..." is poor english - they don't need a sharp image of the star, they just need as much light as possible to put into spectrograph.
And although 99% of astronomers agree they're probably detecting planet-mass objects, there are a couple of people who think they're seeing brown dwarf stars at high orbital inclinations, and they're not planets at all.
> 3 years ago observations on distant supernova
>showed that the expansion of the universe was
>accelerating, a discovery that was utterly
>unexpected and could only be explained by some
>previously unknown repulsive force. eg here
You're wrong. The cosmological constant *was* known about since Einstein, it was just set to zero for all previous models. Astronomers knew about it, it was just that the measured value was zero, within experimental errors.
The SNe experiments with HST finally probed large enough distances to detect at a significant level that the constant turned to be non-zero, and even then, the two competing groups agonized over publication for many months because they knew how it would sound to the community. The fact that both of the groups independently derived similiar results bolstered the idea of a non-zero cosmological constant.
And this *doesn't* violate relativity, either.
> It seemed strange to me that they could be this
wrong and yet still claim to know exactly what
happened in the first few microseconds of the
universe.
Wrong again, I'm afraid. The early universe is suprisingly simple, and the mechanics after 1e-3 seconds are described by high-school level physics. The early universe was a simple place, i.e. simple subatomic particles at a high kinetic energy.
The trouble with this guy's theory is that it's not been independently verified, and his experimental method is poor, to say the least. It's also a bad sign when people get an anomalous result and immediately cry "I've disproved general realtivity!" without thinking about more mundane explanations first.
Actually, it was just getting going in Britain in 1991, and it was called 'packet radio'. You could buy a two meter transciever and a packet box, and you would become a node point, effectively a router and client all in one. I had just bought the packet hardware when this new-fangled internet came to undergrad popularity levels.
AFAIK, the packet box is still unused at my parent's house.... although, I wonder if anyone is still using it - any slashdotters?
I would imagine that it's possible in theory, but the major systematic error would be in the accurate location of the satellite itself. Satellites AFAIK are known to a few meters, but they need constant orbital updating.
You're happily assuming that we'll be more advanced than we are today in 10,000 years time, and that may not be the case.
I thought the whole point of the memorial was that advanced cultures will have no problem picking up the radioactive decay and so avoid it, but if there's a massive disaster and we're back to sticks and stones then the monument would still be effective at scaring people away.
I couldn't find it in the article translation, but is there any mention of what happens if the cooling fails and the cables become non-superconducting? From what little physics I remember, wouldn't the cables heat up explosively?
I'd argue that SETI@home *is* worthwhile, although I admit that the return is more uncertain. The genome isn't going off anywhere soon, whilst a reasonably tranisent ET radio signal (i.e. they broadcast at a star for 10 years then off to the next candidate star) would arguably be a greater discovery.
Genome@home is the 10-year investment bond, whilst SETI@home is the lottery ticket.
Nobody rejected the companion star idea, it's just very hard to carry out a survey for a 20th magnitude brown dwarf in a highly eccentric object. Try diffrentiating that from the hundreds of thousands of other faint objects in motion on the celestial sphere.
"Fringe science" is not ignored by most scientists, it's just that a one-off, realistically unrepeatable observation is not good scientific method.
>but at 1-3lys away, it should show up fairly brightly, I would guess.
Nope, young low mass brown dwarfs *may* be visible (they glow from the heat of gravitational contraction and not thermonuclear burning) but any brown dwarf older than 1 Gigayear would be virtually undetectable even within 0.4 light years. There could be many candidates in the solar neighbourhood, but they're just so damn faint...
OK, this looks like a troll, but I'm happy to feed it...
Ummm, the fibre is wrapped in successive protective layers, which provide mechanical robustness. The transmitting core can be supprounded by up to three layers - a cladding layer of 200 microns, a polyamide etch-resistant coating to bring it up to a quarter millimetre, and then usually a plastic buffer for up to a millimetre, and that's before it goes into a protective conduit....
OTOH, bare fibre is an absolute bastard to handle - I built an astronomical instrument which used fibers *shiver* never again, never again....
A couple of people have asked questions about detecting planets, so here goes...
There are three or four popular methods for looking for planets, and the differences are quite subtle (well, they were to me).
The first method is Doppler velocity detection - the planet and star both orbit about their mutual center of gravity, a point somewhere near the center of the star as the mass of the star >> mass of the planet. The light of the planet itself is not detected, but a spectrograph analyses the stellar light to measure the velocity of the star with respect to the Earth. This is due to the Doppler effect, i.e. the starlight is slightly blue-shifted for the star coming towards us, red-shifted if it's going away.
After subtracting off the eath and sun's velocities, and taking measurements over a few years, a periodic shift is seen in the star's velocity and this is attributed to the gravitational influence of a planet. To date, this is the method that has pulled out all the detections so far.
However, the reflex motion of the star is only about 10 meters/second, and the spectrograph can only detect signals typically bigger than 3 meters/second. Also, only large planets near to the star are easily detectable.
A second method is planet transit - if the orbital plane of the planet is edge-on to the our Solar system, then the planet can move between us and the star and the starlight will dim for a few hours as the planet crosses the sun's disk - the trouble with this method is that you only see planetary systems that are edge on as viewed from Earth. To dats, only one system has been discovered with this method, and even that one was suggested by a Doppler velocity search.
The third method is a variation on interferometry called 'nulling' interferometry, and relies on the wave nature of light. AFAIK, the Keck interferometer is quite a way off achieving this sort of performance, but the trick here is that the light from the two telescopes are combined in such a way that the starlight cancels out but the starlight reflected from the planet's atmosphere is not cancelled out.
One way of thinking of this is looking at a car's headlamp and a bicycle lamp next to each other, and then looking at them through a picket fence. By moving your head laterally you can get one fencepost to block the car headlamp, and get the bicycle lamp light to shine through one of the gaps. The separation of the two telescopes then determines the effective pitch of the fenceposts.
An error in their writing. They meant it's shrunk in one dimension, but the volume of the coin is still the same.
If I knew any better, I think I've been trolled...
Space flight is a risky business
on
The Challenger
·
· Score: 1
I remember seeing the explosion in my primary school in Britain, and the reaction was curiously muted. I admire the other/. posters with their expressions of grief, I truly I wish I had the same intensity of feeling that the posters have, but really, so what? Space flight is an inherently risky business.
Yes, I'm upset that seven fine people died that day, but many hundreds die as part of relatively normal but tragic accidents every day, and where's their mourning? The crew knew the risks. If you had said "You have a 1 in 5 chance of blowing up", you still would have a queue of people halfway down Florida trying to get in.
This national grief strongly reminds me of how many British people reacted the day Diana "Princess of Hearts" died - national shock and mass hysteria. Traumatised school children? Death of a nation's space program? Like "where were you when Kennedy died?" for our generation?
Slashdot Mirror
These supernova follow a reasonably well-known light curve, and so by measuring its apparent brightness and knowing what its actual brightness is, you can get a rough cut at the distance.
If it was in our galaxy, it would be MUCH brighter.
I think you've misunderstood the program slightly.
Gamma Ray Bursts are seen across the sky at a rate of a couple of bursts per day, with the current detection limits. The latest theory is that they are the last stages of a binary pulsar (two neutron stars orbiting each other) spiralling together and just before they coalesce, an intense, beamed burst of gamma rays is emitted from this system. We are seeing the bursts from many millions/billions of light years away, and for us to be detecting them over that distance, the implication is that the energy release is awesome, to say the least.
Any star system in the galaxy in the GRB's beam path is immediately sterilised. It doesn't have to be *our* star, we just have to be in the way of a burster's beam. Thankfully we don't see any binary pulsar systems in our own galaxy that look close to doing this soon.
This is used to great effect in Greg Egan's "Diaspora" which details what happens to the Earth when a GRB goes off nearby, and Stpehen Baxter uses the idea of many GRB's sterilising the galaxy every 100 million years to explain the Fermi Paradox in his great series: "Manifold: Time"
Hope this helps,
Dr Fish
Having used LyX for a couple of years, I've found it to be incredibly useful for many simple documents and poster displays. The one gripe that I have, though, is with the conversion to PDFs when you have embedded postscript files, or the page is a non-standard size. The PDF it produces can be very wonky, and/or suffer from the dreaded "embedded bitmapped font" syndrome which makes PDFs about 10 times larger and look shit on a computer screen.
The good news is that the LyX team are very aware of these kinds of problems and they are very enthusiastic with helping you out, even with simple questions. It's everything you hoped an enthusiastic Linux community would be.
> My biggest problem with modern science (physics
> and astrophysics in particular) is this truly
> inane method of making "conjectural"
> observations...that is, assuming that and
> unobservable activity has been proven simply
> because something observable has occurred.
OK. We know from the distribution of light and the measured rotational velocities of most galaxies we can see that they seem to be embedded in a large halo of gravitating mass. This has been measured and confirmed many, many times over that past 40 years.
When you add up the total amount of emitted light from a galaxy, you can get an estimate of it's mass and that turns out to be about 10**12 solar masses, say.
Looking and the dynamic motion of the galaxy using the Doppler shift of spectral lines from stars in the galaxy, you calculate that the required amount of mass for the galactic motion is roughly 100 TIMES the amount you count up by counting stars/gas/glowing stuff alone.
1) Maybe this 'dark' matter is not being illuminated by stars? No - do the calculations and it turns out that this stuff would be detectable. Instead, we see nothing. So, we can rule out baryonic (protons, electrons, photons) matter. Therefore, it has mass but it doesn't interact with baryonic matter - it is only gravitationally coupled with baryonic matter.
2) Maybe it is condensed into cool stars that we can't see? Again, no luck there. Really dim stars are hard to detect, but over the past 5 years, enough have been detected to make a guess as to whether dark matter is this form. There isn't.
So, we still have no clear idea what dark matter is made up of, but a lot of ideas that we can test. I'll admit that it's incredible, but believe me, there's a lot of evidence for dark matter. Alternative hypotheses, such as modified long-range forces have been tried out and don't work (and no, it's a separate issue from non-zero lambda cosmologies!) so we are back into the 'small, energetic, low mass subatomic particle' game.
What we are NOT doing is inventing dark matter, as you imply. We tend to leave it to the mystics.
If you're interested in the more detailed reasons why, please feel free to contact me.
mak at as arizona edu
The problem comes in formation. Binaries do not coalesce to form larger mass black holes (it's a problem of getting rid of the huge angular momentum storead as the stars orbit each other), except possibly as binary black holes which take many mega-years to spiral into each other via gravitational radiation loss. 14 solar masses is also larger than the sum of masses of most binary systems, and those systems which *do* have large masses don't merge for dynamical reasons (mostly the AM problem above).
The interest is that there's no clear formation mechanism for these medium-sized black holes.
P.S. If a neutrino is chargeless, how do you "fire" one at something?
How about a beam of relativistic charged particles that decay and release neutrinos as a byproduct? Relativistic beaming means most neutrinos in our rest frame are being beamed in the direction of propagation.
Great! Who's getting the Head and Shoulders truck then?
There's been a lot of talk at coffee mornings in our astronomy department about "press release publishing", where scientific results that have not passed through peer review get column inches in the American broadsheet newspapers. Although new results are exciting and the urge to shout them from the mountaintop is strong, it's a very dangerous trend.
The majority of American science departments are trying to crack down on this, but I think it's only a matter of time before we get another "Cold fusion" fiasco in one of the sciences again, and that can't be good for anyone in the research fields concerned.
My parents are both teachers in a local British boys school, and they both think computers are the biggest waste of resources possible.
Both work in the 'Information Resource Centre' (i.e. the library) where sixteen PCs are networked together as an 'information resource', according to President Tony Blair's grand new view of 'A computer on every child's desk' (hmmm, reminds me of another megalomaniac....). The theory is that the kids learn about the computers and how to use them in order to prepare them for the real world which (apparently) has computers everywhere. The truth of the matter is that the boys download tons of porn and set it up to appear as backgrounds on other users' accounts. The school ran out of money for a competent sysadmin and the current poor soul doesn't know how to manage his own arse, never mind the pitted ingenuity of dozens of horny teenagers.
Even as an 'information resource' (gak - horrible phrase!) the Web is basically shit for any reasonably detailed material. Yes it's fun to surf, but when I *really* need to check facts, I go off to a library and get it out of a dead tree tome. Books are critically reviewed, the web is not. GIGO en masse, and most importantly:
1 computer == 50 books.
Palms will only be used for playing games/gossiping/switching the TV on and off when the lesson gets boring, and there are always times when playing *any* game, no matter how crappy and pixellated, will be preferable to listening to a lesson.
Grr, I need a cup of coffee.
I don't think he would've been too pleased to be called a big bang theorist - he was an advocate of the steady state theory, and came up with the name 'big bang' to make fun of the then opposing cosmological theory. Ironically, the name 'big bang' stuck.
I was a graduate student at the IoA in Cambridge (which Fred Hoyle founded), and I met him a couple of times. He was still keeping up with contemporary research and had a few great stories to tell. A very clever man, and sharp as a tack.
His sci-fi books feature (unsuprisingly) a lot of astronomy - I just read "The Black Cloud" and it's a pretty good read, I'd recommend it to anyone interested.
Their funding has been going for at least 10 years, and their technique is as accurate as it sounds. Iodine absorption spectroscopy *is* as accurate as the the numbers claim (about 3m/s at the last look).
The phrase "By focusing extremely precise measuring techniques..." is poor english - they don't need a sharp image of the star, they just need as much light as possible to put into spectrograph.
And although 99% of astronomers agree they're probably detecting planet-mass objects, there are a couple of people who think they're seeing brown dwarf stars at high orbital inclinations, and they're not planets at all.
> 3 years ago observations on distant supernova
>showed that the expansion of the universe was
>accelerating, a discovery that was utterly
>unexpected and could only be explained by some
>previously unknown repulsive force. eg here
You're wrong. The cosmological constant *was* known about since Einstein, it was just set to zero for all previous models. Astronomers knew about it, it was just that the measured value was zero, within experimental errors.
The SNe experiments with HST finally probed large enough distances to detect at a significant level that the constant turned to be non-zero, and even then, the two competing groups agonized over publication for many months because they knew how it would sound to the community. The fact that both of the groups independently derived similiar results bolstered the idea of a non-zero cosmological constant.
And this *doesn't* violate relativity, either.
> It seemed strange to me that they could be this
wrong and yet still claim to know exactly what
happened in the first few microseconds of the
universe.
Wrong again, I'm afraid. The early universe is suprisingly simple, and the mechanics after 1e-3 seconds are described by high-school level physics. The early universe was a simple place, i.e. simple subatomic particles at a high kinetic energy.
The trouble with this guy's theory is that it's not been independently verified, and his experimental method is poor, to say the least. It's also a bad sign when people get an anomalous result and immediately cry "I've disproved general realtivity!" without thinking about more mundane explanations first.
Actually, it was just getting going in Britain in 1991, and it was called 'packet radio'. You could buy a two meter transciever and a packet box, and you would become a node point, effectively a router and client all in one. I had just bought the packet hardware when this new-fangled internet came to undergrad popularity levels.
AFAIK, the packet box is still unused at my parent's house.... although, I wonder if anyone is still using it - any slashdotters?
I'm an astronomer, but not a satellite expert :)
I would imagine that it's possible in theory, but the major systematic error would be in the accurate location of the satellite itself. Satellites AFAIK are known to a few meters, but they need constant orbital updating.
Any GPS experts care to comment?
M.
"...never ssh from any box that is not your desktop..."
I'm intrigued... you can't trust boxes you know nothing about... what's the alternative then?
You're happily assuming that we'll be more advanced than we are today in 10,000 years time, and that may not be the case.
I thought the whole point of the memorial was that advanced cultures will have no problem picking up the radioactive decay and so avoid it, but if there's a massive disaster and we're back to sticks and stones then the monument would still be effective at scaring people away.
I couldn't find it in the article translation, but is there any mention of what happens if the cooling fails and the cables become non-superconducting? From what little physics I remember, wouldn't the cables heat up explosively?
I'd argue that SETI@home *is* worthwhile, although I admit that the return is more uncertain. The genome isn't going off anywhere soon, whilst a reasonably tranisent ET radio signal (i.e. they broadcast at a star for 10 years then off to the next candidate star) would arguably be a greater discovery.
Genome@home is the 10-year investment bond, whilst SETI@home is the lottery ticket.
Ack. Time for coffee.
Nobody rejected the companion star idea, it's just very hard to carry out a survey for a 20th magnitude brown dwarf in a highly eccentric object. Try diffrentiating that from the hundreds of thousands of other faint objects in motion on the celestial sphere.
"Fringe science" is not ignored by most scientists, it's just that a one-off, realistically unrepeatable observation is not good scientific method.
Thank God! I was starting to get tired of waiting....
>but at 1-3lys away, it should show up fairly brightly, I would guess.
Nope, young low mass brown dwarfs *may* be visible (they glow from the heat of gravitational contraction and not thermonuclear burning) but any brown dwarf older than 1 Gigayear would be virtually undetectable even within 0.4 light years. There could be many candidates in the solar neighbourhood, but they're just so damn faint...
Time to but a bigger telescope!
OK, this looks like a troll, but I'm happy to feed it...
Ummm, the fibre is wrapped in successive protective layers, which provide mechanical robustness. The transmitting core can be supprounded by up to three layers - a cladding layer of 200 microns, a polyamide etch-resistant coating to bring it up to a quarter millimetre, and then usually a plastic buffer for up to a millimetre, and that's before it goes into a protective conduit....
OTOH, bare fibre is an absolute bastard to handle - I built an astronomical instrument which used fibers *shiver* never again, never again....
A couple of people have asked questions about detecting planets, so here goes...
There are three or four popular methods for looking for planets, and the differences are quite subtle (well, they were to me).
The first method is Doppler velocity detection - the planet and star both orbit about their mutual center of gravity, a point somewhere near the center of the star as the mass of the star >> mass of the planet. The light of the planet itself is not detected, but a spectrograph analyses the stellar light to measure the velocity of the star with respect to the Earth. This is due to the Doppler effect, i.e. the starlight is slightly blue-shifted for the star coming towards us, red-shifted if it's going away.
After subtracting off the eath and sun's velocities, and taking measurements over a few years, a periodic shift is seen in the star's velocity and this is attributed to the gravitational influence of a planet. To date, this is the method that has pulled out all the detections so far.
However, the reflex motion of the star is only about 10 meters/second, and the spectrograph can only detect signals typically bigger than 3 meters/second. Also, only large planets near to the star are easily detectable.
A second method is planet transit - if the orbital plane of the planet is edge-on to the our Solar system, then the planet can move between us and the star and the starlight will dim for a few hours as the planet crosses the sun's disk - the trouble with this method is that you only see planetary systems that are edge on as viewed from Earth. To dats, only one system has been discovered with this method, and even that one was suggested by a Doppler velocity search.
The third method is a variation on interferometry called 'nulling' interferometry, and relies on the wave nature of light. AFAIK, the Keck interferometer is quite a way off achieving this sort of performance, but the trick here is that the light from the two telescopes are combined in such a way that the starlight cancels out but the starlight reflected from the planet's atmosphere is not cancelled out.
One way of thinking of this is looking at a car's headlamp and a bicycle lamp next to each other, and then looking at them through a picket fence. By moving your head laterally you can get one fencepost to block the car headlamp, and get the bicycle lamp light to shine through one of the gaps. The separation of the two telescopes then determines the effective pitch of the fenceposts.
An error in their writing. They meant it's shrunk in one dimension, but the volume of the coin is still the same.
If I knew any better, I think I've been trolled...
I remember seeing the explosion in my primary school in Britain, and the reaction was curiously muted. I admire the other /. posters with their expressions of grief, I truly I wish I had the same intensity of feeling that the posters have, but really, so what? Space flight is an inherently risky business.
Yes, I'm upset that seven fine people died that day, but many hundreds die as part of relatively normal but tragic accidents every day, and where's their mourning? The crew knew the risks. If you had said "You have a 1 in 5 chance of blowing up", you still would have a queue of people halfway down Florida trying to get in.
This national grief strongly reminds me of how many British people reacted the day Diana "Princess of Hearts" died - national shock and mass hysteria. Traumatised school children? Death of a nation's space program? Like "where were you when Kennedy died?" for our generation?
Puhlease. Give it a rest.