A Matter Of Perspective

   NASA/JPL/University of Arizona 

Do you recall what you were doing at 6:20 a.m. Wednesday morning October 3 last year? That’s a tough one but I feel fairly certain that I was just waking up to the sound of my wife’s hairdryer. At that same moment, the Mars Reconnaissance Orbiter spacecraft took this picture of Earth and moon from Mars orbit. Earth was 85 million miles away and oh-so-small in all that inky black. Yet you can make out some familiar features like clouds, parts of the North Atlantic and South Pacific oceans and even the west coast of South America (at lower right.)

Pictures like this one begin to give us some idea of the jewel that Earth truly is. They also allow us to see things in clearer perspective. Should I really be upset if the guy in front of me is going five miles under the speed limit? You know the answer to that one.

4 Responses

  1. Gary

    I have been told there are no stars visible in any photos from space because of exposure times, contrast, etc, but am wondering how long an exposure to deep space the MRO camera would need to show the stars, if there was nothing else in the field of view to upset the balance? I can’t believe nobody has ever wanted to see the stars from the moon, or ISS, or any other mission.

    1. astrobob

      Gary, I can only speculate those photos aren’t taken because they’re not a mission priority. This would certainly be the case with the HiRISE camera on MRO. Pictures in orbit showing stars would only be possible when the craft was over the nighttime side of the planet. They they’d have to aim it up at an angle to include planet and sky, which I’m not even sure they can do, since its focus is on the landscape below.
      Since there’s no light on the night side of Mars, the disk would be a black cutout against the sky with a bit of limb lighting near sunrise/sunset. The ISS astronauts have photographed the aurora and stars from orbit at night under moonlight and lit by cities below. The Apollo astronauts took some pictures of the Earth in the sky from the moon (same exposure as the sunny lunar surface), but I’ve never heard or seen a photo of stars from the moon. Of course, those guys were extremely busy and had little time for sightseeing. The Mars rovers have photographed the Earth, other planets and even meteors from the surface of Mars. I’ll dig around as there might possibly be one showing stars.

  2. Gary

    “I’ll dig around as there might possibly be one showing stars.”

    Thanks astrobob, I have been looking, and the only offworld astronomy seems to have been done on the Apollo 16 mission, with the FUVC camera/spectroscope.
    http://www.myspacemuseum.com/alsepl1.htm

    And here are some images from the device that a chap spent a lot of time decoding. I don’t know why they would haul that big, heavy device up there and then not make the results known. It was designed by the Naval Research boys, so maybe classified?
    http://www3.telus.net/summa/faruv/index.htm

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