Download Objects in Space

Objects in Space
Meteoroid
 A chunk of rock/dust that can be seen as a track of
light in the sky as it burns up in the Earth’s
atmosphere.
 They are too small to survive the heat of friction
while travel through the Earth’s atmosphere.
Meteorite
 a chunk of rock after it impacts on a planet or moon.
 More simply – a meteoroid that hits a planet or
moon.
 Meteorites have to pass through the atmosphere to
hit the Earth and therefore must be fairly large.
Meteor
 a chunk of rock that is much smaller than an
asteroid.
 Meteoroid that is travelling through space.
 The melted appearance of this specimen suggests
that is actually a meteorite.
Asteroids
 A “minor planet” or non-luminous chunk of rock
that is smaller than a planet, but bigger than a
meteoroid that orbits a star.
 A belt of asteroids can be found between Mars and
Jupiter.
 Some asteroids have been perturbed from their orbits
and travel in elliptical paths through the inner
planets.
Comets
 An object orbiting the sun, often in a very eccentric
elliptical orbit.
 Given the nickname “dirty snowballs” as they are
composed mostly of ice and loose rocky material.
 When comets goes close to the sun, the ice is turned
into vapor and is released in a long, luminous tail.
 Generally originate from a region of space called the
Oort Cloud. Some originate from the Kuiper Belt.
 When comets pass near larger objects, their orbits
are disturbed and they can be directed towards the
sun and form elliptical orbits.
 Many scientists believe that the source of water in
our oceans was due to comet impacts early in our
planet’s existence.
The Oort Cloud
 Is a hypothetical region that is thought to stretch
outward beyond the Kuiper Belt along the plane of
the Solar System.
 Named after Dutch Astronomer Jan Oort who
proposed this region in 1950.
 Its a cloud of debris left over from the formation of
the Solar System and is the source of comets.
Astronomer theorize that it contains over a trillion
long period comets greater 0.6 km in size (some
which take 50 million years to orbit the sun).
 Located beyond the Kuiper Belt
 The Oort Cloud is located from 5000 to 100000 AU
from the sun.
Moons
 A natural satellite that orbits a planet.
 Can travel in elliptical orbits.
 Only moons with sufficient mass form spheres – this
is because they have sufficient gravity to form this
shape.
 Therefore all small moons are irregular in shape.
 There are 4 moons larger than our moon in the Solar
System, but relative to its planet, Earth’s moon is by
far the largest.
Planets
 The definition of a planet became a topic of great
interest in 2006, when the Pluto debate came up!
As a result, planets must meet the following criteria:
1) An object that orbits the sun.
2) An object that is large enough to be spherical
in shape due to a sufficient amount of mass.
3) An object that has an orbit that is not
controlled by another planet.
4) An object whose orbit has been cleared of
asteroids by its gravity.
5) An object that does not emit own light (and is
therefore too small to be considered a star).
Many stars form binary systems in which two
stars orbit each other. Stars need a sufficient
mass of Hydrogen to generate enough gravity
to start a nuclear fusion reaction.
Dwarf Planets and the Kuiper Belt
 Large objects orbiting the sun that does not meet all
of the criteria of a planet
 Discovery of dwarf planets in the Kuiper Belt started
with Eris in 2003. It is believed to be larger than
Pluto.
 It is suggested that there may be hundreds of dwarf
planets in the Kuiper Belt – most of them too distant
and non-luminous to be found. It is also suggested
that they have icy compositions similar to comets
and Pluto.
The Kuiper Belt
 The Kuiper Belt is a doughnut-shaped ring,
extending just beyond the orbit of Neptune from
about 30 to 55 AU.
 Named for astronomer Gerard Kuiper.
 Short period comets originate from the Kuiper Belt
(those with orbital periods less than 200 years)
 It is also the host of many icy dwarf planets
including Pluto (also known as KBO’s (Kuiper Belt
Objects) or TNO’s (trans-Neptunian Objects))
Exoplanets
 There are now thousands of known exoplanets.
Planets that orbit other stars than the sun.
 The first exoplanets were only found 25 years ago.
They are found when they pass in front of a star.
 The search is on to find an Earth-like exoplanet
(especially one that might support life)
Stars
 a self-luminous ball of gas that shines or has shone
because of a nuclear fusion reaction in its interior.
 Extreme temperatures (several million K (kelvin)
and pressures are required to ignite a fusion reaction.
 The sun is our closest star.
 The colour and size of a star can tell an astronomer a
great deal about its lifespan and ultimate future.
Constellations
 Ancient astronomers grouped these stars to form
creatures and objects that we call “Constellations”.
 Predicting your behaviour or future based on these
constellations (particularly the 12 constellations
called the Zodiac) is called astrology. Astrology is
NOT a science.
 The stars in a constellation are not necessarily
located in a group or a star-cluster.
Nebula
 Interstellar region of gas and dust
 If enough gas and dust are present, gravity will draw
the dust together (over millions of years) and the
material could pull together to form a star or a
cluster of stars. (Our Solar System formed like this)
 Nebulas can either emit light, absorb light or reflect
light.
 Nebulas can also result from the explosion of a star
(Nova or Supernova). Gases from the star are
expelled into space.
Galaxy
 A collection of stars, gas, and dust bound together by
gravity
 The smallest galaxies may contain only a few
hundred thousand stars, while the largest galaxies
have thousands of billions of stars.
 Galaxies can be classified based on their shape - this
also gives information about their age
 Galaxies rotate about a central point – the Milky
Way galaxy takes 220 million years to rotate.
Milky Way Galaxy
 The Milky Way galaxy contains our solar system.
 Galaxies come in a variety of shapes (which are
indicative of their age and size
 The Milky Way galaxy contains 200 - 400 billion
stars and is about 120,000 light years across.
Neutron Stars and Pulsars
 stars that have a mass of 1.5 to 3.0 times the mass of
the Sun but a radius of only 10 km. It is the result of
the gravitational collapse of a large star
 This collapse has crushed all matter into neutrons.
 A teaspoon of a neutron star would weigh thousands
of tons.
 If the neutron star emits jets of matter and energy in
a pulsating fashion, it is known as a pulsar. Pulsars
spin rapidly and jets of material are often ejected
from the poles of the pulsar.
Black Hole
 a region in space from which, according to the
general theory of relativity, neither light, radiation,
nor matter can escape.
 Black holes have immense gravity and suck in stars
and other material that get too close to their “gravity
wells”.
 It is believed that a supermassive black hole exists in
the middle of our galaxy (and the middle of most
galaxies. The black holes continue to get larger as
they “suck” in more and more material.
Novas
 When a star dies, the nuclear reaction in the core
stops. Since the outward force no longer exists, the
star collapses onto itself due to its force of gravity.
 This collapse is called a Nova and can be seen from
the outer layers of gas ejected from the imploding
star (A nebula forms that is illuminated by the
collapsed star within).
 When a small star “goes Nova”, it leaves behind a
small star called a white dwarf and a nebula.
Black Holes and Supernovas
 Black holes can only form from the collapse of
supermassive stars. (Those with a mass of more than
about 10 solar masses).
 The explosion will form a supernova. The energy
released in a supernova is so great that the supernova
will outshine every other object in the galaxy for a
period of a few weeks..
 The core of a supernova may become a black hole if
there is sufficient mass.
Supernova
 The explosion of a star with the resulting release of
tremendous amounts of radiation (energy) and dust.
 They only form from the explosion of very massive
stars and leave behind neutron stars or black holes.
 Elements heavier than iron generally only form from
supernovas.
 A supernova will briefly outshine all other stars in a
galaxy.
 The Crab Nebula is the remnant of a supernova
recorded by Chinese astronomers in 1054. It was
exceedingly bright in the night sky for years after.
Quaser
 Quasars or quasi-stellar radio sources are the most
energetic and distant members of a class of objects
called active galactic nuclei.
 Scientists believe they are found at the centers of
super-massive galaxies and surround supermassive
black holes.
 They release so much energy, they “outshine” entire
galaxies over many EM wavelengths.
 They are extremely distant, among the most distant
objects in the universe and likely formed shortly
after the Big Bang (creation of the universe)