Astronomy Picture of the Day 12-15-02

NASA ^ | 12-15-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 December 15

A Network of Microlensing Caustics
Credit & Copyright: Joachim Wambsganss (Ap. Inst. Potsdam)

Explanation: A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic. In the above computer simulated map, caustics are discernible as the sharp bright curved lines. When a background quasar moves across a microlensing caustic, it can appear dramatically brighter. Many astronomers thought microlensing events practically immeasurable even twenty years ago, but within the past five years now hundreds have been found. Precise measurements of microlensing are now providing unique information about the composition and distribution of matter in galaxies and the universe. Some astronomers now predict that future microlensing searches might even isolate planets orbiting distant stars.

[petuniasevan]

On a completely different subject:

Earth and Saturn are almost at conjunction; it will occur on the 17th.
There is a user-friendly thread posted on this subject. Here is the link:

Breathtaking SaturnOn Dec. 17th, Earth and Saturn closest encounter in 30 years

[petuniasevan]

[xJones]

Thank you, and a Microlensing Caustics bump!

[Mama_Bear]

Interesting and colorful. Thanks for the ping.

[WSGilcrest]

Looks like something I made with the fractal program I have.

[glock rocks]

now that would look great down the side of my truck!

[GodBlessRonaldReagan]

Uhhh...my brain hurts! Thanks for the ping!

[RightWhale]

Interesting that gravity lenses form caustics rather than point images. Similar to reflections off the meniscus on a cup of coffee. This is a new tool for astronomers especially since the Hubble telescope came online.

[mikrofon]

A very intriguing image -- 'seems to fit the Holiday season...

(Microlensing Caustics to All! ;^)

[SuziQ]

WHOA, that's cool! Makes me think of fractals.

[SuziQ]

I posted by thoughts (at #10) before I saw your post. Great minds think alike!!

[SuziQ]

Oh bummer!! We're supposed to have snow all tomorrow night through Tuesday, then clouds. We may not be able to see it! I'll have to check online on Wed. to see if there are any images from Tues. night.

[gortklattu]

Big Deal. I saw this when doing windowpane in 1973!