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Old Mars

Mars is further away, we see a smaller image so we

need much better telescopes

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Mars

• Reddish color, easily seen with naked eye– on Earth, red colored rocks are found in deserts

• Roman god of war color of blood (second to Jupiter)

• Astrological symbol is a shield and spear

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• Until photography, all images drawn or painted

• very difficult to compare observations - intervention of the observer

• first image due to Fontana (1636)

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Refractor telescopes

• Simple refractor

• not a sharp image

• colors have a

• different focus

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Based on two lenses

Objective lens - concave

Ocular lens - concave

The same as an opera glass - 3 power

o b j e c t i v e

eyepiece

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• First accurate drawing - Huygens 1659

• first showing of polar caps Huygens 1672

• Mars was seem to have dark and light areas– Dark – water (oceans, seas, bays lakes)– Bright – continents (reddish color)

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Syrtis Major

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1672

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• Herschel 1777-1784

• observed tilt to be ~30 degrees (like Earth)

• therefore, 4 seasons (like Earth)

• concluded that the inhabitants would enjoy a life similar to that on Earth

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Big improvement

• Invention of the achromatic objective lens

• Chester Hall, 1729

• Two different kinds of glass in the objective

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Problems with glass

• 1799

• Swiss, Pierre Louis Guinand

• cast high quality lenses as large as 6”

• worked with Joseph von Fraunhofer, a German optician who did the grinding and polishing

• later lenses were much larger

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Applications of new telescopes

• Heinrick Mädler - school teacher (seminary), amateur astronomer

• met Wilhelm Beer - banker and amateur astronomer

• looked at Mars (map in 1830)

• did not name features

• mapped Moon 1834-1836

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More observations• Mountains of Mitchell, 1845 (B & M)

• use of the term canale; Angel Secchi, 1858 (referred to a channel)

• Dawes, 1860s, names features– also determines relation between size of

telescope and resolution– begins a race for big telescopes

• No standard nomenclature

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Next opposition

• 1877

• new telescope (Alvan Clark) 26” at US Naval Observatory

• new observer; Asaph Hall

• not a professional astronomer

• observed two satellites; Phobos (fear) and Deimos (flight) - reference to Iliad

• only terrestrial planet (except Earth) with satellites

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At the same opposition

• Giovanni Schiaparelli

• accurate measurements of lat. & long. of features

• introduced a nomenclature that stuck (1877)

• showed long, straight, narrow dark makings

• called them canali, again meaning channels

• got translated into canals, artificial

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New features

• Schiaparelli - observed gemination, a splitting of canals

• canals had to be several miles wide to be seen

• must have been vegetation on the banks of the canals

• showed dark areas where canals crossed

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Names

• Light areas - terrestrial or imaginary lands– Arabia, Hellas, Syria, Amazonis

• dark areas - bodies of water– seas - Tyrrhenum mare– bays - Sabaeus sinus– gulfs - Golfo sabeo– lakes - Solis lacus

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Problems in viewing Mars

• Opposition every 2 years and 50 days

• best oppositions every 15 or 17 years

• difficult image at opposition

• next (great) opposition: August 28, 2003– Best in thousands of years!

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New player

• Percival Lowell 1855-1916

• an amateur but a serious one

• was convinced that the canals were artificial

• constructed to irrigate deserts (red color)

• view of Mars as a planet drying out

• Dark areas were not seas but marshes

• Wave of darkening (primary evidence)

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If there is water on Mars• Dark areas, light areas (yes)• clouds (yes)• storms (yes)• reflection of Sun on water (no)

– Reflected light not polarized (no)– but suppose the dark areas are vegetation

• polar caps (yes)• red color (yes)

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Implications of water

• On Earth, water comes from volcanic activity

• volcanoes indicate geologic activity

• volcanoes indicate plate tectonics

• moderate temp. & atmospheric pressure

• as we understand it, life can form under these conditions

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General conclusions, 1877

• Moderate climate

• water available

• large desert areas

• planet losing water

• an ideal place for life

• sentient organisms living there

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Requirements for life

• Moderate temperatures (between 0 and 100 C)

• free water

• an atmosphere– does not have to be oxygen