Possible Exomoon Found

[+DieChecker]

Whether photons really do accelerate is debatable.

From what I've read, light actually does slow down in other mediums then a vacuum. Some special mediums can even get the speed some specific photons down to Newtonian speeds, or stopped all together. Yet, when the light moves into another medium, it immediately increases, or decreases to that mediums speed. There is no actual speeding up or slowing, as I've read, but the transition is instantaneous. I could very well be wrong however.

[Waspie_Dwarf]

The speed of light is some kind of univeral hard limit, I think.

Wow this topic has really been derailed hasn't it? It has very little to do with exoplanets any more!!!

The speed of light in a vacuum is a universal hard limit. Light can travel slower in other mediums. Therefore it is possible for sound to travel faster than light in these circumstances, but the sound is not travelling faster than the speed of light (which IS the speed of light in a vacuum).

I hope that made sense.

All of which seems be lost on tanwha who simply does not see that his idea is unworkable.

tanwha, go outside on a dark night and look at a star, any star. Look at how dim it is. Not even the brightest star can cast a shadow.

Now think about what you want to do. You want to shine a laser across the same distances as that star. You want the light from that laser to be so bright that it will reflect from an exomoon back to the Earth and be detectable with a telescope.

Even taking into account that a laser is directional you are going to have to pump in far more energy than a star uses in order for the laser to be bright enough to be seen when it bounces back to Earth.

The technology to produce a power source far more powerful than a star is pure science fiction. Building a device that could contain that sort of energy without being destroyed in the process is pure fantasy and will probably remain so for ever more.

To put it simply, your idea is unworkable.

Edited April 14, 2014 by Waspie_Dwarf

[Waspie_Dwarf]

Radio astronomy doesn't involve "using" radio frequencies like in sonar or radar. Radio astronomy doesn't involving beaming out radio signals to objects and waiting for a return signal to read. Radio telescopes observe EM radiation in the radio frequency portion of the EM spectrum that some astronomical objects emit.

Not totally true.

Radio telescopes are used as radar systems. There are several topics on this site that I have posted showing radar images (movies in some cases) of asteroids made using this technique. It was also used to measure the rotation speeds of Venus and Mercury before the advent of space probes.

[Waspie_Dwarf]

Using a laser to map a far off solar system certainly is possible,

Hypothetically maybe. Technologically no way.

but would require years of travel time,

In the case of the possible exomoon this topic was supposed to be about, around 3,200 years to get a return signal.

and incredible precision, and a receiver the size of a planet.

And a laser beam more powerful than a star.

[spacecowboy342]

Whether photons really do accelerate is debatable.

Unseen and unknown does not equate to untrue. Take dark energy for example.

Photons don't accelerate. The speed of light is constant in all reference frames. This isn't debatable but observed fact. Unseen and unknown doesn't equal untrue but no evidence doesn't equal true, take esp for example

[+DieChecker]

Hypothetically maybe. Technologically no way.

In the case of the possible exomoon this topic was supposed to be about, around 3,200 years to get a return signal.

And a laser beam more powerful than a star.

To be fair, I was speaking theoretically. It should be possible to focus the beam to the point where you hit the crater and then get a reflection back. But the reciever would have to be big beyond belief. And the quality of accuraccy needed to hit the planet and the quality of focus necessary is very far outside what we can do today. I think the energy necessary would be a function of how tight the beam was.

If we worked at it, we probably could hit Pluto with a beam that gave a fair approximation of the apparent strength of the Sun. It probably would bankrupt nations to do so, but I think we could do it.

[Waspie_Dwarf]

If we worked at it, we probably could hit Pluto with a beam that gave a fair approximation of the apparent strength of the Sun. It probably would bankrupt nations to do so, but I think we could do it.

Which would be a totally pointless exercise given that the New Horizons spacecraft will be flying past Plutoand imaging it's surface in about 15 months.

I think you have hugely underestimated the difficulty of the task.

Pluto is three and a half million times closer to us than this possible exoplanet.

Light obeys an inverse square law, in other word, double the distance and the light is only a quarter as bright. Triple the distance and the light is one ninth as bright.

To achieve what you think might be possible for Pluto at this exomoon the laser would have to be more than 12,000,000,000,000 more powerful.

As of yet we can't even bounce a laser off of OUR Moon with out using special reflectors placed on the surface, and huge telescopes to detect the very faint reflection.

Even at it's closest Pluto is around 10,600 times further away than the Moon. So if we had some laser reflectors on Pluto, to get a reflection visible to telescopes back on Earth the laser would have to be nearly 113,000,000 times brighter than those currently available to astronomers... and that is to just get a reflection, not to use it as a lidar to view a crater.

Take that figure for Pluto and multiply it with the figure for the exoplanet and we get a laser that needs to be over 1,400,000,000,000,000,000,000 times more powerful than those currently in use, and given that there is unlikely to be any convenient retroreflectors on the exomoon this still won't be enough. To use it as aslidar to find craters would require a laser many thousands of times more powerful still.

Are you beginning to see the problem now?

[+DieChecker]

I think you have hugely underestimated the difficulty of the task.

My point is that it is something that could be done.

Pluto is three and a half million times closer to us than this possible exoplanet.

Light obeys an inverse square law, in other word, double the distance and the light is only a quarter as bright. Triple the distance and the light is one ninth as bright

Which is why you use a laser that focuses the light energy into a beam, right? Though it disperses at the same rate, starting with a beam that is already very narrow allows the wattage per area to retain a lot of energy over a longer distance. It is a function of the energy into the beam and the focus of the beam.

To achieve what you think might be possible for Pluto at this exomoon the laser would have to be more than 12,000,000,000,000 more powerful.

As of yet we can't even bounce a laser off of OUR Moon with out using special reflectors placed on the surface, and huge telescopes to detect the very faint reflection

I did say we'd need titanic sensor arrays that would be cripplingly expensive. How hard would it be to sense a return signal from the Moon, without a mirror, using every major telescope in North America in array? I've read that with the Moon's albedo, it would be about 100 times more difficult then using the mirrors.

Even at it's closest Pluto is around 10,600 times further away than the Moon. So if we had some laser reflectors on Pluto, to get a reflection visible to telescopes back on Earth the laser would have to be nearly 113,000,000 times brighter than those currently available to astronomers... and that is to just get a reflection, not to use it as a lidar to view a crater.

I read that some lasers that are used to hit the mirror on the Moon are about 2 watt lasers. So given a facility like CERN that can pump out 200 MW, that a theoretical laser could be built to output 100 million times the energy. And that would be using telescope level focusing. If there was some kind series of morphic lens then the focus could be made a lot tighter. If it was 100 times tighter, then that 100 million watts aimed at Pluto might just return a signal. And that is without a continent sized array watching for the return.

Take that figure for Pluto and multiply it with the figure for the exoplanet and we get a laser that needs to be over 1,400,000,000,000,000,000,000 times more powerful than those currently in use, and given that there is unlikely to be any convenient retroreflectors on the exomoon this still won't be enough. To use it as aslidar to find craters would require a laser many thousands of times more powerful still.

And yet not impossible.

It is simply an engineering problem. As well as a financial problem. The expense would far outweigh any data recovered.

Are you beginning to see the problem now?

Yes, I think I understand the problem. It would be incredibly hard and take an enormous amount of resources and the signal return would be over a very small time span several generations into the future. Very, very, very, very hard to accomplish.

How far away is this supposed Moon? I did not see a reference to how far away it is in the OP link.

Edited April 15, 2014 by DieChecker

[taniwha]

Wow this topic has really been derailed hasn't it? It has very little to do with exoplanets any more!!!

The speed of light in a vacuum is a universal hard limit. Light can travel slower in other mediums. Therefore it is possible for sound to travel faster than light in these circumstances, but the sound is not travelling faster than the speed of light (which IS the speed of light in a vacuum).

I hope that made sense.

All of which seems be lost on tanwha who simply does not see that his idea is unworkable.

So what your saying is that in a vaccuum a tortoise travels faster than sound, yeah yeah. So tell me where does sound energy go in a vaccuum. Has anyone even turned speakers on in outer space to test it out?

tanwha, go outside on a dark night and look at a star, any star. Look at how dim it is. Not even the brightest star can cast a shadow.

Of course not. A star casts light not shadow. Your point please?

Now think about what you want to do. You want to shine a laser across the same distances as that star. You want the light from that laser to be so bright that it will reflect from an exomoon back to the Earth and be detectable with a telescope.

Even taking into account that a laser is directional you are going to have to pump in far more energy than a star uses in order for the laser to be bright enough to be seen when it bounces back to Earth.

The technology to produce a power source far more powerful than a star is pure science fiction. Building a device that could contain that sort of energy without being destroyed in the process is pure fantasy and will probably remain so for ever more.

To put it simply, your idea is unworkable.

Maybe our own suns power can be focused, you might be on to something, in conjunction with gravitational lensing? Yes Why not!

In any case did you further investigate Hartes

lead?

So, you agree they should name the planet "Parma," right?

Harte

From cat toys to Blu-Ray players, we humans like our lasers, but a new crazy-powerful laser under construction in the Czech Republic will have even the likes of Dr. Evil turning red with jealousy. The Extreme Light Infrastructure ELI Beamlines project is an EU-funded lab that astrophysicists and evil masterminds alike will covet the world over.

Due to be switched on by 2017, ELI Beamlines will construct a laser called the High-Repetition-Rate Advanced Petawatt Laser System HAPLS. This bad boy will emit a short laser burst with an intensity of 1023 watts per square centimeter. That's 100,000 times more power than all the power stations in the world can put out combined. It's as if all the energy of the Sun were focused into a single beam about as big as coaster.

Heres a HELL of a lot of science fiction going on right under your nose!....

http://www.dvice.com/2014-2-3/construction-planned-super-laser-more-powerful-sun

Wont be long now my friend not long now

[JesseCuster]

Not totally true.

Radio telescopes are used as radar systems. There are several topics on this site that I have posted showing radar images (movies in some cases) of asteroids made using this technique. It was also used to measure the rotation speeds of Venus and Mercury before the advent of space probes.

A fair point, but I don't fancy scaling that idea up to trying to detect craters on a moon that's hundreds of light years away as opposed mere astronomical units away.

[JesseCuster]

Of course not. A star casts light not shadow. Your point please?

A remark like that makes me realise that any further discussion is clearly not going to be productive.

[Waspie_Dwarf]

A remark like that makes me realise that any further discussion is clearly not going to be productive.

I have to agree that it does rather highlight a stunning lack of understanding of extraordinarily basic science.

tanwha, what exactly do you think a shadow is? How do you think they are formed?

Edited to add:

Whilst we are at it, what do you think sound is?

These are very basic concepts which you have demonstrated no understanding of at all. If you don't understand what light and sound are (and you really don't seem to) how do you think you are in a position to determine what is and isn't possible?

Edited April 15, 2014 by Waspie_Dwarf

[spacecowboy342]

My point is that it is something that could be done.

Which is why you use a laser that focuses the light energy into a beam, right? Though it disperses at the same rate, starting with a beam that is already very narrow allows the wattage per area to retain a lot of energy over a longer distance. It is a function of the energy into the beam and the focus of the beam.

I did say we'd need titanic sensor arrays that would be cripplingly expensive. How hard would it be to sense a return signal from the Moon, without a mirror, using every major telescope in North America in array? I've read that with the Moon's albedo, it would be about 100 times more difficult then using the mirrors.

I read that some lasers that are used to hit the mirror on the Moon are about 2 watt lasers. So given a facility like CERN that can pump out 200 MW, that a theoretical laser could be built to output 100 million times the energy. And that would be using telescope level focusing. If there was some kind series of morphic lens then the focus could be made a lot tighter. If it was 100 times tighter, then that 100 million watts aimed at Pluto might just return a signal. And that is without a continent sized array watching for the return.

And yet not impossible.

It is simply an engineering problem. As well as a financial problem. The expense would far outweigh any data recovered.

Yes, I think I understand the problem. It would be incredibly hard and take an enormous amount of resources and the signal return would be over a very small time span several generations into the future. Very, very, very, very hard to accomplish.

How far away is this supposed Moon? I did not see a reference to how far away it is in the OP link.

You are going to aim this laser at a point where this moon is going to be in 3200 years and hope your receiver is lined up to receive the signal in 6400 years? Sounds like a long shot at best

[+DieChecker]

You are going to aim this laser at a point where this moon is going to be in 3200 years and hope your receiver is lined up to receive the signal in 6400 years? Sounds like a long shot at best

Totally. I think I'll spend the money elsewhere.

[taniwha]

A remark like that makes me realise that any further discussion is clearly not going to be productive.

Strictly speaking you are right. It was nice talking with you.

[taniwha]

I have to agree that it does rather highlight a stunning lack of understanding of extraordinarily basic science.

tanwha, what exactly do you think a shadow is? How do you think they are formed?

My answer was rhetorical.

Edited to add:

Whilst we are at it, what do you think sound is?

My question was rhetorical.

These are very basic concepts which you have demonstrated no understanding of at all. If you don't understand what light and sound are (and you really don't seem to) how do you think you are in a position to determine what is and isn't possible?

Thats a very big IF.

[Harte]

So what your saying is that in a vaccuum a tortoise travels faster than sound, yeah yeah. So tell me where does sound energy go in a vaccuum. Has anyone even turned speakers on in outer space to test it out?

Not to my knowledge. But in my Physics class, the students observed that sound doesn't travel in a vacuum by pumping the air out of a chamber containing a speaker.

Sound energy doesn't reach a vacuum, since the energy of sound involves the compression and rarefication of a substance (like a gas, a liquid or a solid.)

Harte