oct20 mercury

AnnouncementsFriday Oct 20: 

Announcements Friday Oct 20 Exam 2 Next Wednesday Oct 25 Covers Ch. 6-10 ( Telescopes, Earth, Moon, Mercury, Venus Same format as last exam (in class, textbook, calculator, notes) Star Party 2 Next Thursday Oct 26 7pm-8pm Tentative! Weather permitting Homework 9 on website

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Titan Tethys Rhea GAB

Chapter 10, Part1: Sun-Scorched Mercury: 

Chapter 10, Part1: Sun-Scorched Mercury

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87.9/58.6 = 3:2 Tidal resonance Compare: Moon is 3,300 kg/m3

Earth-based optical observations of Mercury are difficult.: 

Earth-based optical observations of Mercury are difficult. Mercury never gets far from the Sun. Mercury is briefly only visible right before sunrise (greatest western elongation) or just after sunset (greatest eastern elongation).

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Earth-based optical observations of Mercury are difficult. The tilt of Earth’s axis and the inclination of Mercury’s orbit combine to make favorable and unfavorable observations.

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Mercury can be observed using radio telescopes such as Arecibo.

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Mercury can be observed using radio telescopes such as Arecibo, which bounce radio waves revealing Mercury’s rotation.

In this image, red indicates strong reflection of the radar signal and yellow, green, and blue, progressively weaker reflection. The bright red dot at the top of the image indicates strong radar reflection at Mercury's north pole. In fact, it resembles the strong radar echo seen from the ice-rich polar caps of Mars.: 

In this image, red indicates strong reflection of the radar signal and yellow, green, and blue, progressively weaker reflection. The bright red dot at the top of the image indicates strong radar reflection at Mercury's north pole. In fact, it resembles the strong radar echo seen from the ice-rich polar caps of Mars.

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Mercury rotates slowly and has an unusual 3-to-2 spin-orbiting coupling. This tidal locking is exactly like the Earth’s Moon (or Jupiter’s satellite Io), but has a 3:2 spin-obit coupling instead of 1:1

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Mercury rotates slowly and has an unusual 3-to-2 spin-orbiting coupling.

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Mercury rotates slowly and has an unusual 3-to-2 spin-orbiting coupling. 1 rotation completed 1.5 rotations completed

Animation of a day on Mercury(Messenger Website)http://btc.montana.edu/messenger/Interactives/ANIMATIONS/Day_On_Mercury/day_on_mercury_full.htm: 

Animation of a day on Mercury (Messenger Website) http://btc.montana.edu/messenger/Interactives/ANIMATIONS/Day_On_Mercury/day_on_mercury_full.htm

Mercury’s surface is inhospitable: 

Mercury’s surface is inhospitable 88 days of daylight and 88 days of night. Daytime temperatures are 430ºC (800ºF) hot enough to melt lead Nighttime temperatures are -170ºC (-270ºF) Cold enough to freeze CO2 and CH4. Earth typically has temperature differences between day and night of about 11ºC (or 20°F) . On Mercury, the Sun moves from east to west, except at perihelion where Mercury’s movement around the Sun outpaces its rotation and the Sun appears to move backwards through the sky.

Images from Mariner 10 reveal Mercury’s heavily cratered surface.: 

Images from Mariner 10 reveal Mercury’s heavily cratered surface. (Earth’s Moon on same scale at right for comparison: Mercury is 2x radius) Mercury (Earth’s) Moon

Images from Mariner 10 reveal Mercury’s heavily cratered surface.: 

Images from Mariner 10 reveal Mercury’s heavily cratered surface.

Images from Mariner 10 reveal Mercury’s heavily cratered surface.: 

Images from Mariner 10 reveal Mercury’s heavily cratered surface. Mariner 10’s three passes all resulted in the same side of Mercury being photographed1

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Scarps, probably cause by surface shrinkage (cracking and settling) as Mercury cooled early in its history

Caloris Basin : Largest feature on Mercury: 

Caloris Basin : Largest feature on Mercury 1300 km

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Edge of Caloris Basin 1300 km (810 mi) diameter

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The Focusing of Seismic Waves creates broken hilly terrain opposite Caloris Basin

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Unusual, hilly terrain opposite the Caloris Basin.

Mercury: Caloris and Scarp Movie: 

Mercury: Caloris and Scarp Movie

Note: Only half surface of Mercury has been imaged (Mariner 10 flyby only saw sunlit half, slow rotation): 

Note: Only half surface of Mercury has been imaged (Mariner 10 flyby only saw sunlit half, slow rotation)

Radar Astronomy of Mercury1. Determined rotation and 3:2 spin-obit coupling (1964)2. Found evidence for ice in polar cap craters (1999): 

Radar Astronomy of Mercury 1. Determined rotation and 3:2 spin-obit coupling (1964) 2. Found evidence for ice in polar cap craters (1999) Arecibo (P.R.) World’s largest radio telescope

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Possible ice deposits at Mercury’s North Pole in permanently shadowed craters.

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PRS 1: Compared with the Earth’s Moon, Mercury is: Much smaller (1/10) and lower density Somewhat smaller (1/2) and lower density Somewhat larger (2x) and lower density Somewhat larger (2x) and higher density Much larger (10x) and higher density

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PRS 2: Which statement is incorrect concerning Mercury? A day (sunrise to sunset) is 88 Earth days Mercury’s orbit is nearly circular Mercury completes one orbital period every 88 Earth days Mercury’s rotational period is 59 days The Sun rises in the East and sets in the West, but reverses its motion near local noon

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PRS 3: Which statement is correct? Orbiting spacecraft have mapped more than 99% of the surface of Mercury The scarps on Mercury’s surface are caused by meteor impacts The inner core of Mercury is largely rock and ice The Caloris basin is not a large crater impact site Ice was discovered on Mercury poles by high resolution spacecraft imaging in 1974