The Lemon Fool

NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!

https://www.ralspace.stfc.ac.uk/Pages/First-instrument-for-the-JWST-is-completed-and-handed-over-to-NASA.aspx

Which moon is it on?

MrFoolish wrote:

NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!

https://www.ralspace.stfc.ac.uk/Pages/First-instrument-for-the-JWST-is-completed-and-handed-over-to-NASA.aspx

Which moon is it on?

I'm more concerned about who put it there!

Is it alight?

Mike4 wrote:

MrFoolish wrote:

NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!

https://www.ralspace.stfc.ac.uk/Pages/First-instrument-for-the-JWST-is-completed-and-handed-over-to-NASA.aspx

Which moon is it on?

I'm more concerned about who put it there!

[Spartacus]
I put the candle on the moon
[/Spartacus]

--kiloran

MrFoolish wrote:

NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!

https://www.ralspace.stfc.ac.uk/Pages/First-instrument-for-the-JWST-is-completed-and-handed-over-to-NASA.aspx

Which moon is it on?

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).

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?

scrumpyjack wrote:Is it alight?

If it is then something must be providing a fairly high concentration of oxygen in its vicinity.

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

NotSure wrote:Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.

Where do you buy your candles?

GrahamPlatt wrote:

NotSure wrote:Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.

Where do you buy your candles?

One of these?
https://en.wikipedia.org/wiki/Peace_Candle_of_the_World

Or https://sillyamerica.com/blog/worlds-la ... e-indiana/

--kiloran

GrahamPlatt wrote:

NotSure wrote:Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.

Where do you buy your candles?

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.

GrahamPlatt wrote:

NotSure wrote:Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.

Where do you buy your candles?

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.

I didn't realise that Jupiter had so many moons — 79 discovered as of this 2018 article, https://carnegiescience.edu/news/dozen-new-moons-jupiter-discovered-including-one-%E2%80%9Coddball%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.

jfgw wrote:

GrahamPlatt wrote:

NotSure wrote:Using round numbers throughout for an 'order or magnitude' estimate, a candle outputs around 100 W.

Where do you buy your candles?

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.

I didn't realise that Jupiter had so many moons — 79 discovered as of this 2018 article, https://carnegiescience.edu/news/dozen-new-moons-jupiter-discovered-including-one-%E2%80%9Coddball%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.

Shouldn't the sperm whale and a bowl of petunias be on your list too?

jfgw wrote:I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot

More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.

Let's hope they find 1, 2, 3 or 5 candles
but not 4
Sorry... I couldn't help myself

MrFoolish wrote:

jfgw wrote:I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot

More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.

It wouldn't surprise be if they had a branch on one of Jupiter's moons.


Julian F. G. W.

jfgw wrote:

MrFoolish wrote:

jfgw wrote:I am opening a book as to which the telescope will find first:
4/5 the candle;
1/1 the teapot

More likely a McDonalds drink cup, on the basis they turn up in litter everywhere.

It wouldn't surprise be if they had a branch on one of Jupiter's moons.


Julian F. G. W.

Ir should be able to spot Bertrand Russell's teapot which is orbiting somewhere between earth and mars

https://en.wikipedia.org/wiki/Russell%27s_teapot

NotSure wrote:

MrFoolish wrote:

NotSure wrote:It is apparently sensitive enough to detect a candle on one of Jupiter's moons!

https://www.ralspace.stfc.ac.uk/Pages/First-instrument-for-the-JWST-is-completed-and-handed-over-to-NASA.aspx

Which moon is it on?

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).

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?

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.

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).

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......

Party pooper Of couse you'd only try at night!

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).....

NotSure wrote:

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......

Party pooper Of couse you'd only try at night!

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).....

If that poops your party you need more rocket fuel.

NotSure wrote:

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......

Party pooper Of couse you'd only try at night!

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).....

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.

Hope that helps....