Download Newton

“It really sucks!”
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Newton
 Isaac Newton (1642-1722) was a British
scientist who first explained how gravity
works.
 His ideas were inspired by seeing an apple fall
from a tree.
 Newton explained why gravity makes all things
fall to the ground and planets orbit the sun.
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Newton (page 2)
 Newton realized that a planet’s orbit depends on
its mass and its distance from the sun.
 The further apart and the lighter two objects are,
the weaker is the pull of gravity between them.
 He figured out that you can calculate the pull of
gravity between 2 objects by multiplying their
mass by the square of the distance between them.
 This calculation allows astronomers to predict
precisely the movement of every planet, star, and
galaxy in the Universe.
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Newton (page 3)
 Newton’s three laws of motion showed that every
single movement in the Universe can be calculated
mechanically.
 Newton’s theory of gravity showed for the first time
why the Moon stays in its orbit around the Earth, and
how the gravitational pull between the Earth and the
Moon can be worked out mathematically.
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Gravity
 is the attraction, or pulling force, between all matter.
 It is what holds everything on Earth on the ground and
stops it from flying off into space.
 It is the same everywhere, it just depends on the mass
of an object and distance between objects.
 It holds Earth together, keeps the Moon orbiting the
Earth, and all other celestial bodies orbiting the sun.
(i.e.Planets; asteroids; comets)
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Gravity (page 2)
 The more mass an object has, and the closer it is to
another object, the more strongly its gravity pulls.
 Black holes have the strongest gravitational pull in the
entire Universe.
 The basic laws of gravity can be used for anything from
detecting an invisible planet by studying the flickers in
another star’s light, to helping the flight of a space
probe.
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Gravity (page 3)
 Orbits are the result of a perfect balance between the
force of gravity on an object (which pulls it inward
towards whatever it is orbiting), and its forward
momentum (which keeps it flying straight onward)
 This momentum is called inertia.
 Since these forces are “balanced” the planet stays fixed
in an orbital path.
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Black Holes
 Places where gravity is so strong that it sucks
everything in, including light.
 They form when a star or galaxy is so dense that it
collapses under the pull of its own gravity shrinking to
a point so small which is called a singularity.
 Around the singularity, gravity is so intense that spacetime is bent into a funnel.
 These may exist at the heart of every galaxy.
 Matter spiraling into a black hole is torn apart and
glows so brightly that it creates the brightest objects in
the Universe – quasars.
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Dark Matter
 Space matter that we cannot see because it does not
give off light.
 Makes up about 90% of the matter in the Universe.
 Astronomers know about it, because its gravity pulls
on stars and galaxies, changing their orbits and the
way they rotate.
 The stars we see in the Milky Way are only a thin
central slice, embedded in a big, bun-shaped ball of
dark matter.
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Dark Matter
 Is of two kinds: the matter in galaxies (galactic), and
the matter between them (intergalactic).
 Galactic DM may be much the same as ordinary
matter, but burned out early on in the life of the
Universe.
 Intergalactic DM is made up of W.I.M.P.s (Weakly
Interacting Massive Particles)
 The future of the Universe may depend on how much
dark matter there is.
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