Which moon is it on?NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!
https://www.ralspace.stfc.ac.uk/Pages/F ... -NASA.aspx
James Webb Telescope
-
- Lemon Quarter
- Posts: 1717
- Joined: March 22nd, 2020, 7:27 pm
Re: James Webb Telescope
-
- Lemon Half
- Posts: 5980
- Joined: November 24th, 2016, 3:29 am
Re: James Webb Telescope
I'm more concerned about who put it there!MrFoolish wrote:Which moon is it on?NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!
https://www.ralspace.stfc.ac.uk/Pages/F ... -NASA.aspx
-
- Lemon Quarter
- Posts: 4130
- Joined: November 4th, 2016, 10:15 am
Re: James Webb Telescope
Is it alight?
-
- Lemon Quarter
- Posts: 3865
- Joined: November 4th, 2016, 9:24 am
Re: James Webb Telescope
[Spartacus]Mike4 wrote:I'm more concerned about who put it there!MrFoolish wrote: Which moon is it on?
I put the candle on the moon
[/Spartacus]
--kiloran
-
- Lemon Slice
- Posts: 793
- Joined: February 5th, 2021, 4:45 pm
Re: James Webb Telescope
I've no idea (and I suspect your question is rhetorical anyway), but, I ran some quick numbers to see if this claim was even remotely plausible (E&OE).MrFoolish wrote:Which moon is it on?NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!
https://www.ralspace.stfc.ac.uk/Pages/F ... -NASA.aspx
Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W. If we assume (for simplicity) that all the power is concentrated the middle of the JW IR band, i.e. at 10 microns, that is around 1e22 photons/s.
Applying the inverse square law, with Jupiter around 600 million km away, and the JW dish of diameter 6.5 m, I make it that 2 or 3 photons/minute could be captured by the JW. So just about plausible with a long exposure and an extremely high SNR?
-
- Lemon Half
- Posts: 8260
- Joined: November 4th, 2016, 3:26 pm
Re: James Webb Telescope
If it is then something must be providing a fairly high concentration of oxygen in its vicinity.scrumpyjack wrote:Is it alight?
-
- Lemon Quarter
- Posts: 2943
- Joined: November 5th, 2016, 2:22 am
Re: James Webb Telescope
If we've already spotted that there's a candle on one of Jupiter's moons, why have we wasted $10b on a telescope that can, at a pinch, do the same thing?
VRD
VRD
-
- Lemon Quarter
- Posts: 1734
- Joined: November 4th, 2016, 9:40 am
Re: James Webb Telescope
Where do you buy your candles?NotSure wrote: Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.
-
- Lemon Quarter
- Posts: 3865
- Joined: November 4th, 2016, 9:24 am
Re: James Webb Telescope
One of these?GrahamPlatt wrote:Where do you buy your candles?NotSure wrote: Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.
https://en.wikipedia.org/wiki/Peace_Candle_of_the_World
Or https://sillyamerica.com/blog/worlds-la ... e-indiana/
--kiloran
-
- Lemon Slice
- Posts: 793
- Joined: February 5th, 2021, 4:45 pm
Re: James Webb Telescope
GrahamPlatt wrote:Where do you buy your candles?NotSure wrote: Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.
Unfortunately for our ancestors, but luckily for the JW, nearly all of those Watts are emitted in the infra-red. The standard number used for a candle seem to be 80 W (about 2 mg of fuel/second), so about 25 candles should be capable of boiling a kettle.
In visible terms, more like 50 mW - they are apparently about 0.05% efficienct.
-
- Lemon Quarter
- Posts: 2401
- Joined: November 4th, 2016, 3:36 pm
Re: James Webb Telescope
A standard British candle was made from spermaceti from sperm whales and emitted about 80W. The French were ahead of the game with a vegan alternative.GrahamPlatt wrote:Where do you buy your candles?NotSure wrote: Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.
I didn't realise that Jupiter had so many moons — 79 discovered as of this 2018 article, https://carnegiescience.edu/news/dozen- ... l%E2%80%9D. Io has an atmosphere of, mostly, sulphur dioxide. I don't know about the other moons. It may be possible to formulate a candle that will burn in such an atmosphere (I am not a chemist). Combustion can occur without oxygen, for example, lithium will burn in nitrogen.
I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot.
Julian F. G. W.
-
- Lemon Half
- Posts: 5980
- Joined: November 24th, 2016, 3:29 am
Re: James Webb Telescope
Shouldn't the sperm whale and a bowl of petunias be on your list too?jfgw wrote:A standard British candle was made from spermaceti from sperm whales and emitted about 80W. The French were ahead of the game with a vegan alternative.GrahamPlatt wrote: Where do you buy your candles?
I didn't realise that Jupiter had so many moons — 79 discovered as of this 2018 article, https://carnegiescience.edu/news/dozen- ... l%E2%80%9D. Io has an atmosphere of, mostly, sulphur dioxide. I don't know about the other moons. It may be possible to formulate a candle that will burn in such an atmosphere (I am not a chemist). Combustion can occur without oxygen, for example, lithium will burn in nitrogen.
I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot.
Julian F. G. W.
-
- Lemon Quarter
- Posts: 1717
- Joined: March 22nd, 2020, 7:27 pm
Re: James Webb Telescope
More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.jfgw wrote:I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot
-
- Lemon Half
- Posts: 5855
- Joined: May 30th, 2021, 6:01 pm
Re: James Webb Telescope
Let's hope they find 1, 2, 3 or 5 candles
but not 4
Sorry... I couldn't help myself
but not 4
Sorry... I couldn't help myself
-
- Lemon Quarter
- Posts: 2401
- Joined: November 4th, 2016, 3:36 pm
Re: James Webb Telescope
It wouldn't surprise be if they had a branch on one of Jupiter's moons.MrFoolish wrote:More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.jfgw wrote:I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot
Julian F. G. W.
-
- Lemon Quarter
- Posts: 4130
- Joined: November 4th, 2016, 10:15 am
Re: James Webb Telescope
Ir should be able to spot Bertrand Russell's teapot which is orbiting somewhere between earth and marsjfgw wrote:It wouldn't surprise be if they had a branch on one of Jupiter's moons.MrFoolish wrote: More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.
Julian F. G. W.
https://en.wikipedia.org/wiki/Russell%27s_teapot
-
- Lemon Slice
- Posts: 871
- Joined: December 9th, 2016, 6:44 am
Re: James Webb Telescope
The original quote is an overstatement. Webb might detect a candle against a dark background at the distance of Jupiter. It could not resolve a candle on a sunlit Jovian moon. This would be a harder problem than discriminating extra-solar planets near a star.NotSure wrote:I've no idea (and I suspect your question is rhetorical anyway), but, I ran some quick numbers to see if this claim was even remotely plausible (E&OE).MrFoolish wrote: Which moon is it on?
Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W. If we assume (for simplicity) that all the power is concentrated the middle of the JW IR band, i.e. at 10 microns, that is around 1e22 photons/s.
Applying the inverse square law, with Jupiter around 600 million km away, and the JW dish of diameter 6.5 m, I make it that 2 or 3 photons/minute could be captured by the JW. So just about plausible with a long exposure and an extremely high SNR?
magnitude of the sun (at 1 AU) -27.
magnitude of Earth (at 1 AU) -4.
Difference 23.
Apparent magnitude of Galilean moons 5
Apparent magnitude of one candela at 6E8km 41
Difference 36.
(I've done some rounding and a lot of simplification but with a difference of 13 magnitudes a factor of 2 or 10,000 hardly matters).
-
- Lemon Slice
- Posts: 793
- Joined: February 5th, 2021, 4:45 pm
Re: James Webb Telescope
Party pooper Of couse you'd only try at night!9873210 wrote: The original quote is an overstatement. Webb might detect a candle against a dark background at the distance of Jupiter. It could not resolve a candle on a sunlit Jovian moon......
Next you'll be pointing out that the candle would be cold anyway as there's no oxygen on Europa (at least not in gaseous form).....
-
- Lemon Slice
- Posts: 871
- Joined: December 9th, 2016, 6:44 am
Re: James Webb Telescope
If that poops your party you need more rocket fuel.NotSure wrote:Party pooper Of couse you'd only try at night!9873210 wrote: The original quote is an overstatement. Webb might detect a candle against a dark background at the distance of Jupiter. It could not resolve a candle on a sunlit Jovian moon......
Next you'll be pointing out that the candle would be cold anyway as there's no oxygen on Europa (at least not in gaseous form).....
-
- Lemon Half
- Posts: 5980
- Joined: November 24th, 2016, 3:29 am
Re: James Webb Telescope
It was probably one of them electric candles, like what Ray Davies sang about in his song "Lola". I guess it would have to be actually, given the oxygen problem.NotSure wrote:Party pooper Of couse you'd only try at night!9873210 wrote: The original quote is an overstatement. Webb might detect a candle against a dark background at the distance of Jupiter. It could not resolve a candle on a sunlit Jovian moon......
Next you'll be pointing out that the candle would be cold anyway as there's no oxygen on Europa (at least not in gaseous form).....
Hope that helps....