Messenger skims past Mercury

NASA's Messenger yesterday successfully completed its first fly-by of Mercury, passing roughly 124 miles (200km) above the surface of the planet. Messenger image of Mercury. Photo: NASA En route to this initial encounter, Messenger's Narrow Angle Camera took the opportunity to snap the approach, as seen in this image taken on …

[Johnny FireBlade]

I'm no astronomer...

...but shouldn't there be stars in the background of those pictures?

[Jason Rivers]

this is great...

...it shows the technology they're using to link to the upload "within a few seconds" but if they can do that, why can I not get a TV signal when I have line of sight to the tower sending me the streams, it's about 3 miles due north from me, the areal is direct in-line, nothing is in the way atall, yet I can only get E4+1 and BBC Parliment....

oh well, back to the topic, is this still in an attempt to use resources from other planets as we've almost depleted our own?

J

[Steve Evans]

@Johnny FireBlade

Must have been cloudy.

[preethi]

Being an American .......

project doesn't mean that they are all faked, may be the odd one, but this is getting ridiculous!!!!

Time to re-align your sources of info.

[Anonymous Coward]

Re: I'm no astronomer...

I'm not either but I expect that this is because the Sun is so bright compared to the background stars they are too weak to show up in a photo.

The lack of stars in the photos is one of the conspiracy theorist's arguments over the 'fake' moon landings but the same argument applies there as well. The brightness of the Sun overwhelms the light from the stars.

[eddiewrenn]

@Johnny FireBlade

I know - this 'conserve energy' madness has got to stop.

[Frank Bough]

You're right...

...you're no astronomer.

[Anonymous Coward]

Stars?

shouldn't there be stars in the background of those pictures?

Not when the camera is set to expose the planet correctly given the sunlight reflecting off it, no. Same goes for pictures taken from the moon. Funnily enough, they are more interested in photographing the planet correctly than the stars that happen to be in the background.

[Anonymous Coward]

@Johnny

It's a question of the relative brightness of the objects. To correctly image Mercury, the camera settings make the stars far too dim to be visible. Conversely, if they had imaged the stars instead, Mercury's image would have been massively over-exposed.

It's the same argument that Moon-landing conspiracists try to use; pointing out that no stars are visible in photos from the Apollo missions. And it's just as easily debunked... ;-)

[Daniel Hutty]

Johnny FireBlade

The craft taking this picture was heading towards the sun - hence the background stars would have been drowned out. In fact, the picture would have had to be adjusted (brightness, contrast etc) to bring out a clear image of the planet against the background glare...

[Simon Goodwin]

No stars

I knew the answer was because they were so dim, when looked at it in comparison to the nearer brightly lit object but thought I had better confirm. Looked it up in google :)

Taken from an astronomers Q&A (about why pictures taken by astronauts dont show stars):

The stars are there and the astronauts can see them if they look away from the sun. The reason that the stars do not show up on the film is that the stars are so dim that the camera cannot gather enough of their light in a short exposure. Our eyes are a lot more sensitive to light than photographic film. A good example of this is when we take a picture with a camera that is back lighted. The photographer can plainly see the features and colors of the object(usually a relative), but when the picture is developed, only the shadow outline can be seen of the person without any features.

Any picture that you may see of stars are from time-lapse photos. To take a time-lapse photo of the stars, the shutter must be left open on the camera in order for the lens to focus enough light on the film for the image to show up. Longer times allow more photons to enter the camera and record the image. The image is built over time from the total number of photons striking the film. The dimmer the object, the longer the film must be exposed because there are fewer photons per unit of time reaching the camera than for a brighter object.

[Paul van der Lingen]

Likewise - no astronomer but..

.. isn't that a stock photo of the surface of the moon?

[The Mole]

@Jason Rivers

My guess is either the booster on your areal is turned off, nackered, or your cabling/connectors are absolutely rubbish/wrapped round power cables etc. The path to your areal could be fantastic but that doesn't help if the path to your tv is pants.

[James Pickett]

Photography

"The photographer can plainly see the features and colors of the object"

True, but that is because the eye/brain can set its sensitivity for whatever it's looking at. A camera has to set an exposure for the whole area, which may or may not resolve what you want it to. Film and digital sensors can be just as sensitive as the eye, but are not variably sensitive across a wide field.

[Johnny FireBlade]

Thanks peeps!

I suspected some kind of exposure issue would be at the root of it. I dabble in photography on an amateur level, so it makes sense to me. :)

[Joe Cooper]

@Paul van der Lingen

Wait til it gets closer. The surfaces of the Moon and Mercury (that we've seen) look very different.

[Anonymous Coward]

But I can't see.....

.....Freddie !