92 lines
3.1 KiB
Plaintext
92 lines
3.1 KiB
Plaintext
.SH
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Annex: events
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.LP
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.BULLET
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.UL "16XX" ,
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.BULLET
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.UL "1784" ,
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first observation of Cepheid variable star.
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.BULLET
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.UL "1908-1912" ,
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Henrietta Swan Leavitt discovers a relation between Cepheid variable stars' brightness and period of their variation.
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And this leads to knowing the distance between these stars: we now can make wild approximations on astonomic distances between us and stars.
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.BULLET
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.UL "1916, general theory of relativity" ,
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a decade-long struggle to create a new theory of gravity by Albert Einstein.
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.br
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This work is also about space and time, and explains not only how objects move in the universe, but also how the universe itself might evolve.
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.BULLET
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.UL "1925" ,
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Hubble publishes his study on spiral
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.I nebulae ,
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where he identified Cepheid variable stars in them (including the
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.I nebulae
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we currently know as Andromeda).
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.BULLET
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.UL "1925, Mount Wilson 100-inch Hooker telescope" ,
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the world's largest at the time.
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.FOOTNOTE1
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We now make ten times bigger telescopes and hundred times bigger in area.
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.FOOTNOTE2
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.BULLET
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.UL "1927" :
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Lemaître shows that the Einstein's equations suggest an expanding universe.
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.BULLET
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.UL "1930" :
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Lemaître proposes an universe beginning in a small point he called
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.I "Primeval Atom" .
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.ENDBULLET
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.SH
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Annex: vocabulary
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.LP
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.BULLET
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.UL "perihelion" :
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point of an orbit where the object (ex: a planet) is the closest from another object (ex: a star).
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.BULLET
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.UL "aphelion" :
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opposite of perihelion, point of an orbit where the object is the farthest from another object.
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.BULLET
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.UL "precession" :
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change in an angle over time.
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This can be the angle of the ellipse formed by the orbital journey of a planet (apsidal precession).
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Or this can be the movement of the rotational axis of an astronomical body, whereby the axis slowly traces out a cone (axial precession).
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Finally, the precession can be a change in the
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.I plane
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of the orbital course (nodal precession), which can be caused by a third gravitational object.
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.BULLET
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.UL "nebulae" :
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.I "fuzzy thing"
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(or cloud) in latin.
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.BULLET
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.UL "Cepheid variable star" :
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star whose brightness varies over some regular period.
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.ENDBULLET
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.SH
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Annex: people involved (and mentionned in the book)
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.LP
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.BULLET
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.UL "Albert Einstein" :
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.BULLET
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.UL "Georges Lemaître" :
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physicist and preist, first to suggest that the universe was expanding in 1927.
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.br
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He started as an engineer, then was a decorated artilleryman in WW1, switched to mathematics, and priesthood in early 1920s.
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Then moved to cosmology and first studied with Sir Arthur Stanley Eddington before moving on to Harvard and receiving a second PhD in physics from MIT.
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.BULLET
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.UL "Arthur Stanley Eddington" :
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astronomer.
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.BULLET
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.UL "Henrietta Swan Leavitt" :
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Harvard College Observatory "computer".
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Discovered the relation between Cepheid variable stars' brightness and period of vacation.
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.BULLET
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.UL "Edwin Hubble" :
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former lawyer, became astronomer.
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Made the first observation of the expansion of the universe.
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.BULLET
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.UL "Harlow Shapley" :
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discovered the Sun wasn't at the center of the Milky Way, and that our galaxy was much larger than we previously thought.
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.ENDBULLET
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