ASTRO 102: Stars, Galaxies, and the Universe is an introductory-level course in astronomy and astrophysics. The first third of the course deals with understanding the history of astronomy, orbits, gravitation, optics, and the properties of light and matter. The second third investigates the Sun and...
-SCONOMY-introducti
Scientific theory is ... A scientific theory must ...
wide variety of
a substantiated explanation for a body of data/observation explain a
not speculation conjecture , ,
or guess observations with few simple principle
a model : a set of objects with properties and relationships supported by
must be a large compellin
,
often expressed pictorially and mathematically body of evidence
failed any crucial
-
must make predictions must not have
tests of its validity
A scientific theory cannot be proven but can be > sometimes contains multiple laws
substantiated by a large body of evidence scient site
Sciencecomesfromthe Latin word
scientific law : (sometimes used Synonymously w/theory) A well-validated descriptive account of behavior
-
under certain circumstances a practical prescription . EX Newton's "Law of Gravity" is use :
for navigation for many decades .
Halemartesof Science#1
Modern science seeks explanations for observed phenomena that rely solely on natural causes
(a scientific model cannot include divine intervention , or supernatural forces
Halemartesof Science#2
science progresses through the creation and testing of models of nature that explains the observations as simply
as possible . (Simplicity = "Occam's razor)
Hallmarks of Science#3
A scientific model must make testable predictions about natural phenomena that would force us to revise or
abandon the model if the predictions do not agree with the observations .
The Idealized Scientific method earth-centered & sun-centered beliefs-
make observations ↳ challenged the Earth-centered idea in which he
Copernicus
proposed the sun-centered model. This provided a far simpler
explanation for the Observations (EX : retrograde motions)
ask a question
↳ Tycho Brahe Challenged Copernicus' idea . He thought Earth mus
↓ be at the center of the solar system . He compiled the most accurat
suggest a hypothesis (1 arc/minute) naked eye measurements ever made
planetary
↓ positions to verify this .
>
- make a prediction &
test doesn't
support hypothesis ;
revise hypothesis or
↓ test supports
hypothesis ; make Astronomy comes from the Latin word astro meaning
-
choose a new one a test : additional predictions
perform -
experiment or
& test them out "Stars"↳ more than stars . Astronomy is the study of
& -
.
celestial objects space , and the physical
-
additional observation
,
universe as a whole .
white of -
measurement
Astronomical unit (AU) : one Al is equivalent to 150 M Kilometers (93m miles)
which is about the distance from the earth to the sun .
Light year (14) distance that light can travel in
:
a year ,
which is about 10 trillion kilometers/6 trillion miles).
↳ unit of distance not time
(a kilometer = 0 6 .
miles
)
, - So NOMY -cate e
Star : A large , glowing ball of gas that generates heat and light through nuclear fusion . It needs to be
not for nuclear fusion to occur . Energy constantly leaks out of it (heat) which is why fusion occurs
Planet : A moderately large object that orbits a star ; it shines by reflected light Planets may be rocky icy, . ,
or gaseous in composition . Big enough that gravity has distorted it into a spherical shape (why asteroid
aren't spherical) significant thing in its orbit which is why Pluto
-
.
It has to be the only
,
is not a planet
anymore ; Pluto is not the dominant thing in its orbit) .
Moon : An object that orbits a planet
solar system A star and all the material that orbits it
:
, including its planet and moons
Nebula An interstellar cloud of gas and /or dust.
:
Galaxy :
A great collection of stars in space all held together by ,
gravity and orbiting a common center .
Universe : The sum total of all matter and energy ; that is everything within and between all galaxies .
,
various ages :
destination light travel time
days months years
, , moon 2 second
generations (30 years)
centuries Millenia ,
sun 8 minutes
biological ages (human evolution Myr)
-
Sirius 8 years
Gyr) geological ages(precambrian
-
Parsec measure of distance not time. A : Andromeda Galaxy 2 5 million years
.
parsec is based on the Astrological unit (the ↳ light travels at a finite speed (300 ,
000 km/s
distance from the earth to the sun) and it's -3 26 4 the farther we look in distance the furt
.
away ,
light-years away. back we look in time .
The distance between planets are huge compared to their sizes
-
↑ on the same scale the stars are thousands of kilometers
, away
The observable universe is 24 billion light-years in radius and contains over 200 billion
galaxies with a total number of stars comparable to the number of grains of sand on Earth.
Light year : distance light can travel in 1 year the farther in space
we look
↳ About 10 trillion Kilometers (6 trillion miles) the farther we go back in time .
2 light-year =
(speed of light) x (2 years
(300 000km/s) X
bomin ,bosea (
C365days
=
,
= 9 , 460 000 000 000 km OR 9 46x10
*
, , , . km- > 1 light-year
UD OV
Earth orbits the sun once a year
e a speed of 200 000 km/nr
↳ ,
↳ & an average distance of 1 AU = roughly Iso million kilometers
↳ w/ a Earth axis tilt of 23 5 .
Earth rotates in the same direction it orbits counterclockwise as viewed from above the North Pole
,
The solar system move) among the stars roughly 70,000 km/hr
The Milky Way rotates roughly 800 , 000 km/nv
The Milky way moves in Local Group & the universe expands
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