Astrophysics Flashcards
Stars are huge balls of (mostly) ____ gas
hydrogen
In the centre of a star, hydrogen nuclei undergo ____ to form helium nuclei
nuclear fusion
how does heat from fusion help balance out inward pull from the star’s own gravity?
The heat from fusion provides a pressure that prevents the star from collapsing under its own gravity
why does speed of a comet change closer to sun?
- transfer of sun’s GPE to KE
- pulled by sun’s strong gravitational force as it gets closer
how are orbits of planet x and planet y different?
- different circumference
- different time period
what does orbital period mean?
The time taken for an object to complete one orbit
what does orbital radius mean?
the separation distance between the object in orbit and the centre of the object it is orbiting
which planets dont have a solid surface?
Jupiter and Saturn are gas giants. Uranus and Neptune are ice giants
what is the solar system?
any object that is bound by gravity to the sun
what are moons, and what type of orbit do they have?
natural satelites that orbit a planet, elliptical orbit.
what is meant by elliptical orbit?
an oval-shaped path, like a slightly elongated circle
what type of orbits do comets and asteroids have?
highly elliptical orbit- very elongated and ver squashed oval like orbits
what objects in space have slightly elliptical orbit?
planets
what are the differences between a planet and a comet?
-a planet revolves around the sun in a fixed orbit
- it does not have any kind of tail
- they have a slightly elliptical orbit
two examples of dwarf planets?
ceres and pluto
hottest and coldest planet?
venus, neptune
why do comets have a tail?
as it approaches the sun, it begins to sublime and vaporize leaving a trail behind
how is the weight and gravity of a planet related?
directly proprtional.
more mass=more gravity force
what is the formula for weigth?
w=mg
weight in newtons
mass in kilograms
gravity force in N/kg
what is a satelite?
anything that orbits a celestial body
what are some examples of artificial satelites and what type of orbit do they have?
-SATNAV
-whether forecasts
-communication and navigation
geostationary orbit, just above equator so only takes a day to complete. or polar orbit (from north to south)
what provides the centripetal force to keep planets and satellites in orbit?
gravitational force.
what is the resultant force on planets causing them to stay in orbit?
centripetal force in the middle of the planet.
