Astronomy

Famous Astronomers Ptolemy : Earth- centered universe Copernicus : Sun- centered universe

Ptolemy: Geocentric

Copernicus: Heliocentric

Newton Sir Isaac Newton introduced the theory of gravity. That all objects in the universe are attracted to other objects. This idea explained why all objects orbit the most massive object in the solar system.

Gravity Controls EVERYTHING

Orbits Because of Gravity An orbit is a fall that is the same arc as the object it is falling toward.

Moon Orbit

Seasons As the earth tilts the seasons change.

Why do we have seasons?

The Moon

The Moon controls the tides on Earth

TIDES What are tides? –The periodic rise and fall of the sea level under the gravitational pull of the moon Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores.

Moon Tide The Moon’s gravity exerts a strong pull on Earth. The water bulges outward as Earth and the Moon revolve around a common center of mass. The moon’s gravity pulls on the earth, and pulls the water towards it. The water moves up into a slight bulge on the side of the earth that faces the moon.

The Sun Tide The sun’s pull can heighten the moon’s effects or counteract them, depending on where the moon is in relation to the sun.

Spring Tides Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon.Sun

Neap Tides Neap tides are especially weak tides. Moon & Sun are perpendicular to each other. Moon & the Sun’s gravity cancel each other out.

Tidal Range The tidal range is the difference between the level of the ocean at high tide and low tide.

Phases of The Moon

Half of the Moon is always lit up by the sun. As the Moon orbits the Earth, we see different parts of the lighted area.

The revolution of the Moon around the Earth makes the Moon look as if it is changing shape in the sky.

This is caused by the different angles from which we see the lighted part of the Moon's surface. These are called "phases" of the Moon.

The Moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The phases always follow one another in the same order: New moon First quarter Third quarter Full moon

This is caused by the different angles from which we see the lighted part of the Moon's surface. These are called "phases" of the Moon.

New Moon The lighted side of the Moon faces away from the Earth. This means that the Sun, Earth, and Moon are almost in a straight line, with the Moon in between the Sun and the Earth. The Moon that we see looks very dark

New Moon

First Quarter Moon The right half of the Moon appears lighted and the left side of the Moon appears dark. During the time between the New Moon and the First Quarter Moon, the part of the Moon that appears lighted gets larger and larger every day, and will continue to grow until the Full Moon.

First Quarter Moon

Third (Last) Quarter Moon Sometimes called Third Quarter. The left half of the Moon appears lighted, and the right side of the Moon appears dark. During the time between the Full Moon and the Last Quarter Moon, the part of the Moon that appears lighted gets smaller and smaller every day. It will continue to shrink until the New Moon, when the cycle starts all over again.

Third Quarter Moon

Full Moon The lighted side of the Moon faces the Earth. This means that the Earth, Sun, and Moon are nearly in a straight line, with the Earth in the middle. The Moon that we see is very bright from the sunlight reflecting off it.

Full Moon

There are also four other phases of the Moon sometimes used.

Waxing Crescent Moon This Moon can be seen after the New Moon, but before the First Quarter Moon. The crescent will grow larger and larger every day, until the Moon looks like the First Quarter Moon. ("Waxing" means increasing, or growing larger.)

Waxing Crescent Moon

Waxing Gibbous Moon This Moon can be seen after the First Quarter Moon, but before the Full Moon. The amount of the Moon that we can see will grow larger and larger every day. ("Waxing" means increasing, or growing larger.)

Waxing Gibbous Moon

Waning Gibbous Moon This Moon can be seen after the Full Moon, but before the Last Quarter Moon. The amount of the Moon that we can see will grow smaller and smaller every day. ("Waning" means decreasing, or growing smaller.)

Waning Gibbous Moon

Waning Crescent Moon This Moon can be seen after the Last Quarter Moon and before the New Moon. The crescent will grow smaller and smaller every day, until the Moon looks like the New Moon. ("Waning" means decreasing, or growing smaller.)

Waning Crescent Moon

Phases of the Moon

Eclipse When a shadow of a celestial body falls onto another an eclipse occurs.

Solar Eclipse Occurs when the moon passes between the earth and the sun.

Lunar Eclipse Occurs when the moon Earth passes between the Sun and the Moon.

Lunar Eclipse Full at Night Solar Eclipse New Daytime

Movement of Stars Stars appear to move because the earth moves.

Movement of Stars Stars change places in the sky depending on where earth is on its revolution around the sun.

Magnitude Apparent Magnitude is how bright a star appears from Earth. Absolute magnitude is how bright the star actually is.

Constellations Constellations are sections of the sky that contain recognizable star patterns.

The Big Bang Theory

The Big Bang The theory that the entire universe began with one large explosion.

How They Think it Happened The contents of the universe were compressed into a very dense sphere. It exploded and continued to move outward. Then it all came together to form galaxies.

Galaxies Spiral Elliptical Irregular

The Milky Way The Spiral Galaxy in which we live.

Solar System

The Solar System

Inner Planets Mercury – closest to the sun Venus – hottest due to greenhouse effect Earth – the only planet with life Mars – strong evidence for water

Outer Planets Jupiter – largest planet Saturn – largest rings made of icy particles Uranus – rotation is 90 degrees of earth’s Neptune – atmosphere of visible clouds