Carl Sagan - cfas.org

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Carl Sagan (1934-1996) American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences

Transcript of Carl Sagan - cfas.org

Page 1: Carl Sagan - cfas.org

Carl Sagan (1934-1996)

American astronomer, astrophysicist,

cosmologist, author, science popularizer and

science communicator in astronomy and natural

sciences

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Vega (Alpha Lyrae)

The fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively close star at only 25 light-years from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.

Vega's spectral class is A0V, making it a blue-tinged white main sequence star that is fusing hydrogen to helium in its core. Vega will become a class-M red giant and shed much of its mass, finally becoming a white dwarf.

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Summer Triangle

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Mythology of Lyra

In Greek mythology LYRA represents the instrument which was a gift from Apollo to his son Orpheus. The latter's bride, the beautiful Eurydice, had been killed by a viper and was lost in the underworld. Orpheus set out to try to save her and played such sweet music on his lyre that Hades, King of the Underworld, was charmed into giving permission for Eurydice to follow her husband home. He made one proviso, however, that Orpheus should not turn back to look at Eurydice until they were safely out of Hell. The pair set off but, at the very last moment, Orpheus could not resist turning round to see if Eurydice was following him and she was lost forever.

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Roman mosaic Museo Archeological Regionale di Palermo

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Orpheus with the lyre and

surrounded by beasts

(Byzantine & Christian Museum, Athens)

Able to charm all living things and even stones

with his music

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Nymphs Listening to the Songs of Orpheus Charles Francois Jalabert - 1853

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M57 (NGC 6720) is a planetary nebula formed when a shell of ionized gas is expelled into the surrounding interstellar medium by a red giant star passing through the last stage in its evolution before becoming a white dwarf. The Ring Nebula is described variously as bipolar, prolate spheroid, or torus-shaped.

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A Spitzer Space Telescope infrared image of the Ring Nebula (M57) gives a very different picture from the visible color one, bringing out lots of detail not seen at other wavelengths.

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IC 1296 with M57

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IC 1296 is a barred spiral galaxy with a low surface brightness that lies in line of sight 4' to the northwest of the planetary nebula M57. IC 1296 is much farther away - an estimated distance of ~221-million light-years (NED data) as compared to M57's mere 2300LY.

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M56 (NGC 6779) is a globular cluster of classification X. It was discovered by Messier in 1779. Located almost midway along a line between Albireo (β Cygni) and Sulafat (γ Lyrae), it is a challenge to find with large (50–80 mm) binoculars, appearing as a slightly fuzzy star, but can be resolved using an 8 in (20 cm) or larger telescope.

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NGC 6791 is an open star cluster discovered by Friedrich Winnecke in 1853. At roughly 8 billion years old, and with an Iron to Hydrogen abundance ratio that is more than twice that of the Sun, it is one of the oldest and most metal-rich clusters in the Milky Way. This is contrary to the typical rule-of-thumb where older means more metal-poor. Compounded with the fact that it has an unusually high population of stars, NGC 6791 is among the most studied clusters in the sky.

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NGC 6745 (aka UGC 11391) is an irregular galaxy about 206 million light-years (63.5 mega-parsecs) away in the constellation Lyra. It is actually a triplet of galaxies in the process of colliding.

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Epsilon Lyrae (ε Lyr, ε Lyrae), also known as the Double Double, is a multiple star system approximately 162 light-years away.

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