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astronomy Oct. Exam
Terms in this set (54)
How is a star created
gravity compresses material in a cloud so the center becomes dense and hot, generating energy by nuclear fusion. The lightweight atomic nuclei smash together and stick to make heavier nuclei.
What happens when a star dies
the star lives as long as it can generate energy from fusion and dies when it finally exhausts its usable fuel.
what is the measurement of 1 light year in km
9.46 trillion km, or approx. 10 trillion km
what was the cloud that gave birth to our solar system made out of
98% hydrogen and helium and 2% other elements
Which planets are considered jovian planets (gaseous)
Jupiter, Saturn, uranus and neptune
which planets are made of rocks and metals
earth, mercury, mars and venus
What gases is earth predominately made of
carbon, nitrogen, oxygen and iron
what is the speed of light
at this speed of light, how many times could you circle earth
8 times in a second
what does a light year represent
the distance that light can travel in one year (about 10 trillion km)
how long does light take to reach earth from the moon
how many minutes does it take to reach earth from the sun
how far is the andromeda galaxy from earth
2.5 million light years
how much larger is the sun than any other planet in the solar system
by a factor of more than a thousand
how big is the Great Red Spot on Jupiter (what is comparable in size to it)
it could swallow earth whole
what are the properties of a regular planet
(1) orbits a star (but is itself neither a star nor a moon); (2) is massive enough for its own gravity to give it a nearly round shape; and (3) has cleared the neighborhood around its orbit.
properties of a dwarf planet
Objects that meet the first two criteria but that have not cleared their orbital neighborhoods—including Pluto, Eris and the asteroid Ceres—are designated dwarf planets
list of electromagnetic spectrum in order of increasing frequency and decreasing wavelength
radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
what is the nearest star system to our own
on a cosmic calendar when did the big bang happen,
For a universe that is about 14 billion years old, how much time does each month on the cosmic calendar represent
a little more than a billion years
how old is the universe
14 billion years old
on a cosmic calendar scale, when was the milky way galaxy created
on a cosmic calendar when did life on earth come about
when did dinosaurs become extinct
65 million years ago (only yesterday on a cosmic calendar)
which way does earth rotate on its axis
west to east which is why we see the sun rise in the east and set in the west
Earth's average orbital distance is called an astronomical unit, or AU, what's its equivalence in km
equivalent to about 150 million kilometers
At all times at what speed are we racing around the Sun
100,000 km per hour
Earth's orbital path defines a flat plane that we call what
the ecliptic plane
Earth orbits the Sun in the same direction that it rotates on its axis: what is the direction
counterclockwise as viewed from above the North Pole.
where is most of the mass of the galaxy located ?
outside the visible disk, in what we call the halo.
What is this mass called
we call it dark matter because we have not detected any light coming from it (outweighs the mass that makes up the planets and stars)
What are two astonishing discoveries made by Hubble in 1920
1. Virtually every galaxy outside the Local Group is moving away from us. 2. The more distant the galaxy, the faster it appears to be racing away
Why is it that the more distant the galaxy, the faster it appears to be racing away
because the universe is expanding
how fast do we spin around Earth's axis? How fast does Our solar system move among the stars of the local solar neighborhood? at typical speeds of 70,000 km/hr? what about the center of the Milky Way Galaxy?
more than 1000 km/hr, typical speeds of 70,000 km/hr, a speed of 800,000 km/hr.
What constellation are we looking at when facing the galaxy's central bulge
how much larger is the sun in diameter to the moon
the sun is about 400 times larger in diameter than the moon
Is it earth or the center f the universe that rotates and what is the effect
It is Earth that rotates, not the rest of the universe, and that is why the Sun, Moon, planets, and stars all move across our sky each day.
Do Stars near the north celestial pole rise and set?
no they do not rise or set; rather, they remain
above the horizon and make daily counterclockwise circles
around the north celestial pole.
Do stars near the south celestial pole rise and set?
Stars near the south celestial pole never rise above the horizon at all.
Since the earth rotates west to east how do stars rise ad set
stars rise in the east and set in the west
what does latitude affect in the universe
affects the locations of the horizon and zenith relative to the celestial sphere
what is the altitude of the celestial pole in your sky
what star is the north celestial pole close to
What causes seasons
the tilt of Earth's axis causes sunlight
to fall differently on Earth at different times of year
how long is a day
23 hours and 56 minutes
how do we measure a day
by timing how long it takes any star to make one full circuit through our sky, or a sidereal day
what is a 24 hour day or solar day
the average time it takes the Sun to make one circuit through the sky.
How did ancient people recognize
the days on which the solstices and equinoxes occur
by observing the Sun in the sky.
When are the only two times when equinoxes occur
The equinoxes occur on the
only two days of the year on which
the Sun rises precisely due east and
sets precisely due west
Why does precession occur ( a gradual
wobble that changes the orientation of Earth's axis in space)
It is caused by gravity's effect on a tilted,
rotating object that is not a perfect sphere. A spinning top precesses because Earth's gravity tries to pull over its lopsided, tilted spin axis. Gravity does not succeed in pulling it over—at least until friction slows the rate of spin—but instead causes the axis to precess. The spinning Earth precesses because gravitational tugs from the Sun and Moon try to "straighten out" our planet's bulging equator, which has the same tilt as
Aside form the sun what is the brightest, most noticeable object in the sky
When does a lunar eclipse happen
when Earth lies directly between the Sun
and the Moon, so that Earth's shadow falls on the Moon
when does a solar eclipse happen
occurs when the Moon lies directly between the
Sun and Earth, so that the Moon's shadow falls on Earth. People living within the area covered by the Moon's shadow will see the Sun blocked or partially blocked from view
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