space Flashcards
examples of major bodies
Planets
examples of minor bodies
moons, asteroids, comets
order of planets from the sun
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
The four inner planets are
small and rocky
What is an asteroid?
piece of rock that orbits the sun
The four outer planets are
large and mostly composed of gas. known as gas giants
what is the asteroid belt?
giant ring of asteroids between mars and jupiter
what are comets made of?
dust and ice
how do comets orbit the sun?
elliptical paths
what evidence is there that the planets were formed at the same time?
orbit the sun in the same direction and plane
what exists between all masses?
a gravitational force of attraction
how is the gravitational force of attraction affected by mass?
increases with mass
how is the gravitational force of attraction affected by distance?
decreases with distance
what does the gravitational force do?
Acts toward centre of every mass
Keeps you on earth
Keeps moon and satellites in orbit around earth
Keeps comets and planets in orbit around sun
what is a satellite?
a body that orbits another body
natural satellites of the sun
eight planets, comets, asteroids
natural satellites of planets
moons
4 main purposes of artificial satellites
communications
earth observation
astronomy
weather monitoring
What is a polar satellite?
satellite that orbits the poles while the earth spins below, allowing large areas of the earth to be imaged
what does a polar satellite do?
takes photographs for weather forecasting and spying
What is a geostationary satellite?
satellite that orbits the equator in the same direction as the earth rotates
how do geostationary satellites appear from earth?
appear to remain stationary above the same point on earths surface
Uses of geostationary satellites
telephone and TV satellite communications
advantage of having a telescope in space
can take photos without blurring, allowing much greater detail to be seen
what is a nebula?
large cloud of dust and gas
How is a protostar formed?
gravity causes the cloud to collapse and the gas loses gravitational potential energy, which is converted to thermal energy. the hot core is the protostar.
what is a main sequence star?
A stable stage in the life cycle of a star.
Nuclear fusion occurs, fusing hydrogen nuclei into helium nuclei.
There is a balance between the outwards radiation and the force of gravity pulling inwards.
How is a main sequence star formed?
as the protostar accumulates more gas and dust, temperature and density rises. when temperature and density are high enough nuclear fusion takes place, the star is in the main phase of its life and is called the main sequence star.
how are planets formed?
leftover gas and dust forms a rotating disc around the protostar. gravitational forces pull particles together and over millions of years form planets.
nuclear fusion reaction equation
H + H –> He + energy
Which stars will become nebulas, white dwarfs and then black dwarfs?
stars similar in mass to the sun
how does a star that is similar in mass to the sun form a red giant.
Stage reached when almost all hydrogen has been converted into helium by fusion.
Gravitational forces and thermal expansion no longer balanced.
Star starts to collapse.
Layer of hydrogen surrounding core allows fusion to happen.
Energy released causes star to expand and form red giant.
how does a star similar in mass to the sun form a nebula?
when the red giant is at the end of its life, gravitational force can no longer hold outer layers of gas. outer layers flow, cool and surround core to form nebula.
how does a star similar in mass to the sun form a white dwarf, then a black dwarf?
over time, the core cools to form a white dwarf. eventually all fusion stops and the star becomes a black dwarf.
how does a star more massive than the sun form a red supergiant?
The rate at which helium fusion occurs is more rapid than smaller stars. the huge amount of energy pushes the outer layers of the star outwards to form a red supergiant.
what is formed by fusion in stars?
all naturally occurring elements up to iron
how do stars more massive than the sun form a supernova?
gravity causes the supergiant to collapse, releasing energy, causing outer layers to heat up. the outer layers of gas are ejected in an explosion called a supernova.
how is a supernova detected?
an increase in brightness for a short period of time
how is a black hole created by a star more massive than the sun?
after a supernova, the core of a star is left behind. gravity causes it to collapse further, and protons and electrons combine to form neutrons, producing a neutron star. massive stars continue to collapse and form a black hole
black holes have
such a strong gravitational field nothing can escape, including light
Evidence there is hydrogen and helium in the sun
Joseph von Fraunhofer looked at absorption spectrum of light and found it contained many dark lines, called Fraunhofer lines
major gases by mass in the sun
hydrogen 71%, helium 27% and oxygen 1%
What was the big bang?
the whole universe started as a super dense ball that suddenly exploded releasing a huge amount of energy and matter. universe began to expand at enormous speed
where did the big bang come from?
single point called a singularity
what happened after the big bang?
Universe made of high energy radiation and quarks. Period of rapid expansion, causing universe to cool down as it got bigger.
Quarks came together to form protons and neutrons.
Further expansion and cooling allowed hydrogen isotopes to form.
Further expansion and cooling allowed electrons to combine with neutrons and protons to form hydrogen atoms.
what does red shifted mean?
light from distant galaxies has longer wavelengths, shifted towards red end of spectrum (doppler effect)
what does red shifted light from distant galaxies tell us?
supports big bang theory. suggests all galaxies are moving away from us very quickly.
what does the fact that more distant galaxies have greater red shifts tell us?
more distant galaxies are moving away faster than nearer ones. whole universe is expanding
what does the fact that more distant galaxies have greater red shifts tell us?
more distant galaxies are moving away faster than nearer ones. whole universe is expanding
apart from red shift, what other evidence is used to support the big bang theory?
Cosmic Microwave Background Radiation.
many think it is echo of the big bang, no other explanation for CMBR.
what is a light year?
the distance light travels in one year
what is the nearest star to earth and how far is it?
Proxima Centauri, 4.2 light-years away
4 reasons why it is impossible to visit any planet outside solar system
- flight would last many generations
- space craft too slow
- can’t carry enough fuel, oxygen, water
- no possibility of return to earth
2 ways to detect exoplanets
radial velocity method and transit method
what is the radial velocity method?
Movement of a star relative to an exoplanet can be identified through Doppler effect. wavelength of light detected due to changes in movement of star
what is a transit?
when an exoplanet orbiting a star passes between earth and star
what is the transit method?
transit results in a small but detectable drop in brightness of the star orbited by an exoplanet. used to determine existence of exoplanets
how are the elements in a planetary atmosphere identified?
when light is examined, black lines in absorption spectrum allow us to identify elements in atmosphere
how does studying the planetary atmosphere help determine the possibility of life?
used to determine existence of oxygen and water, which might indicate possibility of life
how does intercepting radiowaves help determine the possibility of life on other planets?
radiowaves are constantly monitored in search for messages beyond solar system, and sent out in several languages
how does looking for methane help determine possibility of life on other planets?
methane is produced by living creatures. if methane exists in atmosphere, living creatures must be constantly producing it.
