Final Review
How large is the Sun's radius, compared to the Earth?
108/109 earths
what is the sunspot cycle?
11 yr. cycle that goes to maximum area
What is the temperature at the Sun's core?
15 Million Degrees
Full moon occurs every __________ days.
28
the sun will exhaust its nuclear fuel in about....
5 billion years
What is the temperature of the sun's photosphere?
6000 degrees
How long does it take for light to travel from the Sun to the Earth?
8 Light Minutes
Who used the gravitational force to describe the motion of planets around the sun?
Newton
Name the layers of sun above photosphere.
Photosphere, Chromosphere, Corona
Why is the sun's energy produced only in the core?
Requires extreme heat which can only be founded in the core--so that nuclear fusion takes place
The name of the star that appears brightest in the NIGHT sky is
Sirius
Star A has apparent brightness 2 and Star B has apparent brightness 8. Which star appears brighter in the sky?
Star A (less to more)
An astronomical unit (AU) is defined as
average distance between sun and earth
What can we say about the size of the sun in the next 2-3 billion years?
it does not change
The corona of the sun is only rarely visible because
it emits very little visible light compared to the sun's photosphere
Sun is known as a normal star, but it appears very bright because
it is very close to the earth
why don't we see chromosphere all the time?
light emitted from the photosphere is TOO bright therefore it blocks & cant be seen
Light pollution is caused by
light from objects OTHER than we intend to observe
The total amount of energy a star gives off
luminosity
absolute brightness (M) depends on the...
luminosity (NOT DISTANCE) @ 10 pc
Most stars plotted on the H-R- diagram would fall into a region called
main sequence
The sun is known as a ..... star
main sequence
Stars that lie in different places on the main sequence of the H-R- diagram different from each other mainly having different
mass
Shooting star is a
meteor
Compared to the Jovian planets, on the average, terrestrial planets are
more DENSE and less MASSIVE
A star has apparent brightness 3 and absolute brightness 1. The distance to this star from the earth is
more than 10 pc
What is convection?
movement of material (air or liquid) from one place to another
Phase of the moon during SOLAR ECLIPSE is
new moon
Which of the following is NOT a telescopic discovery of Galileo?
new planet Pluto
Most abundant element of the earth atmosphere is
nitrogen
Astronomers identify the main sequence of the H-R- diagram with what activity in the course of a star's life?
normal life fusing hydrogen in to Helium
The sun produce energy by means of
nuclear fusion
the source of energy responsible for the Sun's high luminosity is....
nuclear fusion
The number of confirmed stars in OUR SOLAR SYSTEM
only 1
What force balance the gravity of the sun?
outward radiation force
the visible part of the sun is called...
photosphere
What model did Copernicus and Kepler have in common?
planets move around the sun
Luminosity depends on...
size & temperature
Resolution of how well you can observe distinct objects thru telescope depends on
size of the telescope
what is granulation?
small grain-like features that cover entire solar surface except for the sunspot regions
White dwarfs compare to main sequence of stars of SAME MASS would always be:
smaller
chromosphere is visible only during...
solar eclipse
what features appear occasionally above the sun's surface?
solar flares, prominences, and sunspots
Why doesn't the Sun collapse under its own gravity?
state of equilibrium
what can you say about the mass of the sun?
sun constantly losing mass--decreases
What force keep planets in their orbit around the sun?
sun's gravity
Color of stars depend on its
temperature
The horizontal axis of H-R- diagram plots...of stars
temperature
Asteroids revolve around
the Sun
Comets revolve around
the Sun
what is the color of the sun?
white & yellow (at peak intensity)
How far is the Sun from the Earth?
1 AU
In which ways can heat be transferred from a hotter to a colder region (with out Medium)?
Convection
What is the hottest part of the entire sun?
Core
Where does the Sun produce most of its energy?
Core
What region has the highest temperature above photosphere?
Corona
What are sunspots?
Dark patches on the surface
Babylonians used deferent and epicycles to explain the retrograde motion of planets. True or False
FALSE
Circumpolar stars never appear ABOVE horizon. True or False.
FALSE
Color of light depends on how FAST light travels. True or False.
FALSE
During emission of light electrons in an atom move from lower orbits to higher orbits. True or False
FALSE
Galileo is the first astronomer to suggest the sun is at the center of the solar system. True or False.
FALSE
Path of the sun among stars is called zodiac. True or False
FALSE
The objects that exhibit retrograde motion are planets and nearby stars. True or False.
FALSE
Who use the telescope to observe the sky first?
Galileo
The largest planet in our solar system is
Jupiter
Which planets' composition is most similar to that of the Sun?
Jupiter
What temperature of stars are expected to live the longest?
M (coldest)
In our solar system, which planet is NOT a member of the Jovian planets>?
Mars
According to Kepler's second law planets move FASTER when they are closer to the sun. True or False.
TRUE
Relative to the horizon, stars rise in the east and set in the west every day. True or False
TRUE
What is the photosphere?
Visible part of the sun
how old is the sun?
about 5 billion yrs. old
The atmosphere of Venus is
about 95% carbon dioxide
The magnitude of a star, based on how luminous, is its
absolute magnitude
AM and PM stand for...
before and after sun crosses the meridian
Most asteroids in our solar system lie
between Mars and Jupiter
Two stars, A & B, has same color. This implies that
both stars have the same temperature
How do we classify stars?
by temperature: O B A F G K M
What causes the greenhouse effect?
carbon dioxide
Composition of asteroids mainly
carbonates, silicates, or metallic
What is the solar wind?
charged particles ejected from surface of the sun
What is the main function of a telescope?
collect more light than our eye capable of
what causes the granulation?
convection; tops of deep gas columns where energy transported by convection
why do sunspots appear dark?
cooler spots & temp drop to about 4000 degrees
Why is one part of the Sun's interior called Radiation Zone?
core energy travels to surface by electromagnetic radiation
How do we measure distance stars using parallax method? What 2 measurements are required?
d = 1/p and (parallax angle & baseline needed)
Light year is used to measure
distance
apparent brightness (m) depends on the...
distance & luminosity
Apparent brightness of a star depends on its
distance and luminosity
What are the granules on the sun's surface due to?
due to convection currents
Mercury is heavily cratered. But we don't see that many craters on the earth. This is because
earth has thick atmosphere compared to Mercury
According to Copernicus planets appear to retrograde when
earth overtakes planets
What causes the day and night on the earth?
earth's rotation about its axis
According to Kepler, planets move around the sun in _________ orbits.
elliptical
Why is one part of the Sun's interior called Convection Zone?
energy transferred by moving gases
Origin of Comets is most likely
frozen objects from outer solar system
What is the most abundant element in the Sun?
hydrogen
what are the 2 main gases in the sun?
hydrogen & helium
The main sequence lifetime of a star with HALF the MASS OF THE SUN
is LONGER than that of the Sun