PTYS_411_511_8_Lec19-032707_Mars2 - Mars continued Dust...

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PTYS/ASTR 206 Mars (cont.) 3/27/07 Mars … continued Mars’s atmosphere Dust devil on as seen by rover Spirit
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PTYS/ASTR 206 Mars (cont.) 3/27/07 Announcements Reading Assignment for 1 st lecture after the exam – Chapter 14 All previous assignments have been graded and handed back – please pick up all of your material since I will be clearing out the boxes later this week – Uncollected assignments will be in my office Exam #2 on Thursday Brief review after today’s lecture Next study-group session is tomorrow (3/28) from 10:30AM-12:00Noon – in room 330. Public lecture – tonight at 7:30PM in 308 of Kuiper (this room). Prof. Bob Brown, “Saturn seen through infrared eyes” – Look for PTYS/ASTR206 sign-up sheet (our class!) Note – Prof. Brown will conduct a limited number of special 10-minute tours of the VIMS Operations Center; these tours will originate in the Atrium at 6PM – early arrival is recommended!
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PTYS/ASTR 206 Mars (cont.) 3/27/07 Today Mars’s red color Mars’s Atmosphere Water on Mars Moons Life on Mars – later in the course For now, suffice it to say that we have NOT detected any life on Mars. This is covered in Chapter 13. But, we will discuss it further in a few weeks.
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PTYS/ASTR 206 Mars (cont.) 3/27/07 Mars’s red color Mars is red because it’s surface contains a lot of iron which is oxidized by its atmosphere Iron is abundant in the lowlands Iron easily loses 2 or 3 of its electrons when coming into contact with, for example, Oxygen (which mostly exists in the form of CO 2 in Mars’s atmosphere) This oxidizes the iron and makes it red Dark regions on Mars can change shape with the Martian season (due to dust storms) and have a different composition than the brighter areas Note that Moon also contains iron in the Mare, but because it has no atmosphere, it is just dark gray, and not red
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PTYS/ASTR 206 Mars (cont.) 3/27/07 The Atmosphere of Mars very tenuous ! the surface air pressure is only about 0.75% of the average on Earth The air pressure on Earth at about 40km in altitude (about 5 times higher than Mt. Everest) is about the same as at the surface of Mars Discovered by noting cloud formations Difficult to determine chemical composition from spectroscopy Very weak greenhouse effect raises the surface temperature by only 5 o C
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PTYS/ASTR 206 Mars (cont.) 3/27/07 Mars’s Atmospheric Composition Mostly CO 2 (95%) with only a trace of O 2 and H 2 0. Small amount of Methane is intriguing discovered in 2003 by Earth-based telescopes, confirmed by Mars Express Orbiter). Unstable gas – sunlight would destroy it in about 100 years What is it origin? Life? Volcanic vents? Comet impact?
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PTYS/ASTR 206 Mars (cont.) 3/27/07 The Mars Sky is Yellowish Dust particles in the atmosphere scatter all wavelengths nearly the same This should make the sky white Because of the presence of magnetite in the dust, blue light is absorbed Leaving a yellowish sky
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This note was uploaded on 01/01/2011 for the course PTYS/ASTR 411/511 taught by Professor Shanebyrne during the Spring '08 term at University of Arizona- Tucson.

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PTYS_411_511_8_Lec19-032707_Mars2 - Mars continued Dust...

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