Grade 9 astromony test Flashcards
define Astronomical Unit
approx. 150 million km; distance from earth to sun
define Astronomy
the scientific study of whats beyond earth
Define Black hole
an extremely dense quantity of matter in space from which no light or matter can escape
define comet
a chunk of ice and dust that travels in an long orbit around the sun
define costellation
a grouping of stars seen from earth
define eclipse
a darkening of a celestial object to the postion of another celestial object
what is the sun
a medium sized star
what is a planet
a large celestial object that travels around a star
what are the 8 planets that travel in our solar system in order
mercury venus earth mars jupiter saturn Uranus neptune
What are the terms of a planet
size, composition, atmosphere, length of day
are planets luminous
no, the refect light, they do not give off light
what is a moon
a satellite , 4 times smaller then earth
what is a galaxy
a huge collection of stars, gas, dust and planets
what is our galaxy
the milky way
where are the dwarf planets
a region of outer solar system known as Kuiper belt
composition of asteroid belt and location
rock and metal, orbits around mars and jupiter
what are meteor/ids/ites made of
a piece of rock or metal
What was the theory called that believed that earth was the center of the solar system
geocentric
Our current model of the solar system is called
heliocentic
who proved the heliocentric model?
Galileo Galiee
Why do we have day and night on earth
because of the rotation of the earth
why do we have seasons?
because of the axis earth is on
what is a solstice
an astronomical event that occurs 2 times each year when the tilt of the earths axis is most inclined toward or away from the sun , causing the position of the sun in the sky to appear to reach its northernmost or southern most extreme
whats an equinox
the time of year when the hours of daylight equal the hours of darkness
In 120000 years which star will the earth be pointing to
Vegas
What is retrograde motion
the apparent motion of an object in the sky, usually a planet, from east to west, rather than its normal motion from west to east.
what rays does the sun give off
electromagnetic waves, consist of X-rays, Gamma Rays and visible light rays.
What is nuclear fusion
is the process where two atoms of hydrogen fuse together to form an atom of heluim
what are the 6 layers of the sun
thermonuclear core, radioactive zone, convection zone, photosphere, chromosphere, corona
which is the hottest part of the sun
core
coldest part of the sun
corona
how many days does it take for the sun to make one full revolution
25 days
define sunspots
Darker cooler area’s on the photosphere cause by the disturbances in the suns magnetic field.
define solar flare
found near sunspots, release of large quantities of gas & charged particles.
Define solar prominence
slow, low energy, gas ejection zones traveling through the corona
how much is one au
150000000km
what is a lunar eclipse
when the sun, earth and moon are alined and the earth casts a shadow over the moon.
whats a solar eclipse
when the moon is the in middle casting a shadow on the earth
where are high tides
facing the moon and oppisate of the moon
where are low tides
on the opisate 2 sides of the moon
what are the 8 phases of the moon in order
first quarter, waxing cresent, new, waning crescent, third quarter, waning gibbous, full , waxing gibbous
what are the characteristics of stars
colour, temperature, size, and brightness
whats the chemical compostion of most stars
helium
what does hot colour mean
cold
what does blue colour mean
hot
what are the 2 factors to determine how bright a star looks from earth
apparent and absolute
what does apparent mean
seen from earth
what does absolute mean
brightness of a star would have if all stars were the same
what are 2 things an astronomer measure to calculate a star/s absolute brightness
distance and luminosity
a light year us equal to
9.46 x 10 to the power of 12 km
how old is our sun
5 billion years old
what are the 4 main types of galaxies
elliptical, spiral, lenticular, irregular
