APOD: Martian Sunset (2014 Mar 02)

[APOD Robot]

Martian Sunset

Explanation: What would it be like to see a sunset on Mars? To help find out, the robotic rover Spirit was deployed in 2005 to park and watch the Sun dip serenely below the distant lip of Gusev crater. Colors in the above image have been slightly exaggerated but would likely be apparent to a human explorer's eye. Fine martian dust particles suspended in the thin atmosphere lend the sky a reddish color, but the dust also scatters blue light in the forward direction, creating a bluish sky glow near the setting Sun. Because Mars is farther away, the Sun is less bright and only about two thirds the diameter it appears from Earth. Images like this help atmospheric scientists understand not only the atmosphere of Mars, but atmospheres across the Solar System, including our home Earth.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

[Nitpicker]

Lonely.

[Boomer12k]

"Sunlight dims over Martian soil,
The night comes soon, there is no toil.

Phobos or Deimos soon may rise,
and Spirit watches o'er Martian Skies.

Alas in the sand, its mission spent,
A final transmission signal was sent.

Unable to reach the final rim,
Spirit's life was made to dim.

On it's journey, it had a friend,
Now Opportunity must reach the end."

:---[===] *

[Ann]

Ann

[Tszabeau]

Looks like someone set up a yurt, on the horizon.

[starsurfer]

It almost looks like something out of a science fiction motion picture! I wonder what Gene Roddenberry would make of this image?

[rstevenson]

It almost looks like something out of a science fiction motion picture! I wonder what Gene Roddenberry would make of this image?

That's his yurt. Mine is just over the hill.

Rob

[Beyond]

Now that i know what a "yurt" is, it doesn't look like a yurt to me.

[George Kaplan]

Actually, the surface brightness of the Sun's disk is the same from all the planets. The fact that there is less sunlight on Mars is due entirely to the smaller size of the disk.

[geckzilla]

Actually, the surface brightness of the Sun's disk is the same from all the planets. The fact that there is less sunlight on Mars is due entirely to the smaller size of the disk.

APOD explanations tend to be simplified and avoid terms like "surface brightness" because it's easily misunderstood by most lay persons. But it's good to have some clarity on the matter.

[Chris Peterson]

Actually, the surface brightness of the Sun's disk is the same from all the planets. The fact that there is less sunlight on Mars is due entirely to the smaller size of the disk.

Yes, but that's also substantially a restatement of the inverse square law.

[rstevenson]

Actually, the surface brightness of the Sun's disk is the same from all the planets. The fact that there is less sunlight on Mars is due entirely to the smaller size of the disk.

... and the smaller size of the disk is due to Mars being farther away from the Sun, as stated in the description >> "Because Mars is farther away, the Sun is less bright ". No one would read that as the Sun being intrinsically less bright, so no pedantry required.

Rob

[Fun Key Brakes]

It looks like the horizon is as far away as you usually see it on Earth until if you factor in the size of the sun as it appears from much futher away.

[Nitpicker]

It looks like the horizon is as far away as you usually see it on Earth until if you factor in the size of the sun as it appears from much futher away.

That depends on how tall you are and also how close your eyes are to this APOD.

[huaande]

There is a always lot of focus on the visual aspect. I wonder why none of the rovers have carried sound recorders to give us the sounds of Mars. The picture calls out for the sounds of a chill wind.

[Chris Peterson]

There is a always lot of focus on the visual aspect. I wonder why none of the rovers have carried sound recorders to give us the sounds of Mars. The picture calls out for the sounds of a chill wind.

The thing is, every instrument is extremely expensive due to the massive amount of validation required (a simple microphone could end up costing millions), and every gram devoted to one device takes away from others. Sound probably doesn't produce much useful information. If someone can demonstrate an important enough science requirement (in comparison with all the other science requirements), you'll see a microphone on some mission. Indeed, there was a microphone on the Mars Polar Lander, which crashed on the surface and never returned any data.

[neufer]

• King Henry VIII Act 5, Scene 4

Porter: These are the youths that thunder at a playhouse,

• and fight for bitten apples; that no audience, but
  the Tribulation of Tower-hill, or the limbs of
  Limehouse, their dear brothers, are able to endure.
  I have some of 'em in Limbo Patrum, and there they
  are like to dance these three days; besides the
  running banquet of two beadles that is to come.

Mars Exploration Rovers Update:
by A.J.S. Rayl, 2014/04/07

<<Opportunity is emerging from a Martian winter with the energy of a kid rover. This veteran robot's energy rocketed 150 watt-hours in March, jumping from 492 watt-hours to 642 watt-hours. In the gentle valley of Cook Haven, bedrock is clearly exposed and the ubiquitous dust of Mars is obviously less prevalent. "I think it's a scour zone, where winds are coming out of [Endeavour Crater] and then scouring the bedrock and the tops of the solar panels to boot," said Ray Arvidson, deputy principal investigator, of Washington University St. Louis. Another 2500 meters to the south is one of the mission's major, much-anticipated science destinations, Cape Tribulation. Cape Tribulation is harboring really ancient, Noachian Period stuff from 3 to 4 billion years ago. "There's a valley that cuts right though Cape Tribulation and the walls are full of different kinds of clay," enthused Arvidson. "And they're all old rocks. The fact that you can see the third dimension means we can look at the bedded plains and the strata proper and can see the style alteration. Because we have the Bench, which is like a super highway, Cape Tribulation is not that far away." >>

Much more at: http://www.planetary.org/explore/space- ... haven.html