Physics and Astronomy

[JustChecking]

To start of the "traditional P&A thread" here's view of Earth and Moon from Mars...

[corky]

  very very beautiful...THANK YOU JO....     

[JustChecking]

thank you, darling



After 5 years of analysis of the WMAP (Wilkinson Microwave Anisotropy Probe) data, we finally got results!

The goal of WMAP was to create "all sky temperature map"; according to the results, average "temperature" is 2.725 Kelvin (-270.435 C or -454.783 F), with fluctuations circa 0.0002 K.

Thanks to these precise measurements, scientists were able to determine age of the Universe (according to current cosmological models) - 13.73 +/- 0.12 billion years.

Another result of the analysis is the content of the Universe today:
- atoms - 4.5%
- dark matter - 23%
- dark energy - 72%

and content of the Universe when age of Universe was 380,000 years (at the end of the photon epoch - epoch when the energy of the universe is dominated by photons, after most leptons and anti-leptons annihilated at the end of the lepton epoch - see Timeline of the Big Bang for more details):
- neutrinos - 10%
- atoms - 12%
- photons - 15%
- dark matter - 63%

Last but not least - within the limits of instrument error, the geometry of the universe is flat.

for more see:
- LAMBDA - WMAP Parameters Summary
- WMAP Results
- Timeline of the Big Bang
- WMAP on WikiPedia, with many useful links

[phil]

The Cassini spacecraft captured this color portrait of Saturn and Titan
only a few minutes before the haze-enshrouded moon slipped behind
the planet's enormous bulk.
The view looks toward the sunlit side of the rings from about 5 degrees
below the ringplane.

The northern hemisphere of Titan (5,150 kilometers, 3,200 miles across)
presently appears darker than the south, a feature presumed to be
a seasonal effect.

Images taken using red, green and blue spectral filters were combined to
create this natural color view. The images were acquired with the Cassini
spacecraft wide-angle camera on Jan. 29, 2008 at a distance of approximately
2.3 million kilometers (1.4 million miles) from Titan and 1 million kilometers
(630,000 miles) from Saturn. Image scale is 135 kilometers (84 miles)
per pixel on Titan and 61 kilometers (38 miles) per pixel on Saturn.

 

[Don]

"Dark matter" reminds me of a humorous thing I once read about:

       Flanaghan's Finangling Factor: The number which you need to multiply your answer by to get the answer you should have gotten.

Science and engineering has more of these than we would like to admit. The thing about dark matter is that you can't see it or touch it and nobody can tell you what it is. It's there to make the equations work.


@Phil: Thanks for the Saturn pic. The starship Cassini continues on its voyages. The moon Enceladus has water spewing out of it, so maybe there are some creatures swimming around out there.

[JustChecking]

"Dark matter" reminds me of a humorous thing I once read about:

       Flanaghan's Finangling Factor: The number which you need to multiply your answer by to get the answer you should have gotten.

Science and engineering has more of these than we would like to admit.

Well, that's for sure, on the other hand, you have to have at least some numbers to start with - you can't derive any number out of "nowhere", you need to start from something; e.g. all non-quantum physics can be built upon the value of speed of light and charge of electron - all the rest comes out of the theory...
Lets not get this confused with the numbers that "magically" appear in equations - physicists do use phrases like "nature likes pretty numbers", but that's not reason most equations contain numbers like 2, 1/2, 1.732... (square root of 3), etc.; all these "pretty" numbers come out of integration - dimension of space is whole number after all, ain't it?

Then again, the quantum theory (esp. the supersymmetry and string theories) sure have quite a few "parameters" - e.g. supersymmetry in most formulations has about 10 parameters; yet, lets not forget that these are typically "situated" in more dimensions, thus we need more "start numbers" to get to our universe, with just fewer dimensions...

The thing about dark matter is that you can't see it or touch it and nobody can tell you what it is. It's there to make the equations work.

That's true, and to many people (and some 10 years ago also to many scientists) this was a big problem; but lets not forget that e.g. electrons and protons as such do not exist also (and I'm not talking only about the particle-wave duality) - they're simply a mathematical concept that is easier to grasp if presented as an existing "particle" (as wonderfully described in Surely You're Joking, Mr. Feynman! when he asks philosophers what does the "abstract concept" mean)... the same goes for all particles of the Standard Model, quarks, photos, etc. ...

[phil]

Saturn's moon, Dione, photographed by Cassini, about 403,000 miles away.
Lit by the Sun on the left,  and reflection back off of Saturn from the right.

[corky]

OOOOOOOOOOOOOOOOOH...so beautiful& amazing picture...thanks for sharing dearest Phil...

[Don]

Mars landing today!!! The Phoenix lander should be touching down on Mars on May 25th at 4.53 PDT. The lander has a little chemistry lab on board and a robot arm to dig up some soil to run experiments on.  It is going to land in an area where there is expected to be ice just under the surface. Hope all goes well! 

[Don]

TOUCHDOWN!!!  They made it!!!       

[Don]

[img width= height=]http://members.aol.com/schrodinger333/phoenix3.jpg[/img]
[img width= height=]http://members.aol.com/schrodinger333/phoenix4.jpg[/img]

[phil]

E x c e l l e n t!
The first successful rocket propelled landing on Mars since 1976! 

[Don]

E x c e l l e n t!
The first successful rocket propelled landing on Mars since 1976! 

Yes indeed, although there was also Mars Polar Lander which disappeared about 10 years ago. Phoenix is carrying some  experiments similar to those on that ill-fated mission, plus some others from a cancelled lander which was supposed to land in 2001.

First Pictures....

[img width= height=]http://members.aol.com/schrodinger333/phoenix5.jpg[/img]
.

[img width= height=]http://members.aol.com/schrodinger333/phoenix6.jpg[/img]

[JustChecking]

thanks for keeping this thread up to date!

some amazing news!

[phil]

   
   Unbelievable photo of the landing!...
 
   

Mars Reconnaissance Orbiter's  camera acquired this image of Phoenix hanging from its parachute as it descended to the Martian surface.
Shown here is a 10 kilometer (6 mile) diameter crater informally called "Heimdall," and an improved full-resolution image of the parachute and lander.
Although it appears that Phoenix is descending into the crater, it is actually about 20 kilometers (about 12 miles) in front of the crater.