The Dotted Dunes of Mars
Explanation:
What causes the black dots on dunes on Mars? As spring dawns on the Northern Hemisphere of Mars, dunes of sand near the poles begin to defrost. Thinner regions of ice typically thaw first revealing sand whose darkness soaks in sunlight and accelerates the thaw. By summer, the spots will have expanded to encompass the entire dunes that will then be completely thawed and dark. The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas. Taken in mid-July, the above image shows a field of spotted polar dunes spanning about 3 kilometers near the Martian North Pole. Meanwhile, in the Southern Hemisphere of Mars, the Earth-sent robot Martian rovers will try to survive through Martian winter, which peaks in mid-September.
Astronomy Picture of the Day
An education isn't how much you have committed to memory,
or even how much you know. It's being able to differentiate
between what you do know and what you don't.
-- Anatole France
In a consumer society there are inevitably
two kinds of slaves:
the prisoners of addiction and the prisoners of envy.
-Ivan Illich, priest
(1926-2002)
There is a two-letter word that perhaps has more
meaning than any other two-letter word, and that is "UP."
It's easy to understand UP, meaning toward the!
sky or at the top of the list, but when we waken
in the morning, why do we wake UP?
At a meeting, why does a topic come UP? Why do
we speak UP and why are the officers UP for
election and why is it UP to the secretary
to write UP a report?
We call UP our friends And we use it to
brighten UP a room, polish UP the silver,
we warm UP the leftovers and clean UP
the kitchen. We lock UP the house and
some guys fix UP the old car.
At other times the little word has real special meaning.
People stir UP trouble, line UP for tickets,
work UP an appetite, and think UP excuses.
To be dressed is one thing but to be dressed UP is special.
And this UP is confusing:
A drain must be opened UP because it is stopped UP.
We openUP a store in the morning but we close it UP at night.
We see m to be pretty mixed UP about UP!
To be knowledgeable of the proper uses of UP,
look UP the word in the dictionary.
In a desk size dictionary, takes UP almost 1/4th
the page and definitions add UP to about thirty.
If you are UP to it, you might try building UP a list of the
many ways UP is used. It will take UP a lot of your time,
but if you don't give UP, you may wind UP with a
hundred or more.
When it threatens to rain, we say it is clouding UP.
When the sun comes out we say it is clearing UP.
The word "UP" has soooooo many meanings
When it rains, it wets UP the earth.
When it doesn't rain for awhile, things dry UP.
One could go on and on, but I'll wrap it UP,
for now my time is UP, so............. now
I'll shut UP
I was driving the other day and came up on a VW Beetle
with a license plate reading 'BOBS MG'.
I was able to pull up beside the car at the next light,
so I said to the driver, "Hey, that's not an MG."
The driver looked over at me and said, "I'm not Bob."
If a small one kiloton nuke went off in Newark,N.J.
Swinburne University of Technology's center for micro-photonics
have constructed a model of the Sydney Opera House, seen in this
undated photo, that is about half the diameter of a human hair.
With dimensions of 64 x 38 x 41 micrometers, or more than a
million times smaller than the real Sydney structure, the model
was built from a hybrid material of glass and polymer by firing
intense laser light into the matter in a liquid state to create what
to the human eye appears as an almost imperceptible dot,
but under an electron microscope it contains the detail and the
beauty of the iconic Sydney harbour side structure.
(AP Photo/Swinburne University, ho)
China has shaken off the humiliation it has suffered
in the past at the hands of the Western imperialist
powers and is becoming a nation once more to be
reckoned with.
