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AstronomyThe scientific study of the universe
Scientist who study the universe are called what?Astronomers
What are some important things astronomers do?Discover new stars, galaxies, planets, & black
holesProtect Earth against objects that may hit us
The UniverseGalaxy – a collection of stars, dust, and gas
bound together by gravity.Our solar system is part of what galaxy?
Milky-Way GalaxyWhat are some things found in our solar
system?EarthSunOther planetsSmall asteroids and comets
Measuring Distances in Spaceastronomical unit the average distance
between the Earth and the sun; approximately 150 million kilometers (symbol, AU)
Astronomers also use the speed of light to measure distance
Light travels at 300,000,000 m/s. In one year, light travels 9.4607 x 1012 km. This distance is known as a light-year.
Earth’s RotationRotation – The spin of a body on its axisDoes the Earth rotate from west to east or
east to west?West to east
At any given time, Earth’s hemisphere facing the sun is experiencing daylight and the Earth’s hemisphere away from the sun is experiencing night time.
Earth’s Rotationperihelion the point in the orbit of a planet
at which the planet is closet to the sunaphelion the point in the orbit of a planet at
which the planet is farthest from the sunEarth’s orbit around the sun is an ellipseAn ellipse is a closed curve whose shape is
determined by two points, or foci, within the ellipseEarth is not always the same distance away from
the sun
The Revolving EarthRevolution – the motion of a body that travels
around another body in space; one complete trip along an orbitEarth’s revolution around the sun causes seasons to
occur.At what speed does the Earth travel around
the sun?29.8 km/s
How long does it take Earth to orbit the sun? Be specific!365 ¼ days ~ 1 year
The Foucault PendulumHow did we figure out the Earth was
spinning?A brilliant man used a pendulum!
Jean-Bernard-Leon Foucault – scientist who provided evidence of Earth’s rotation by using a pendulum
http://www.youtube.com/watch?v=S2id35aQH0s
The Coriollis EffectThe rotation of Earth causes ocean
currents and wind belts to curve to the left or right.
This curving is caused by Earth’s rotation and is called the Coriolis effect.
Earth’s RotationQuestion: What’s one way we can prove the
Earth is rotating?As the night passes, the constellations move in
the sky. (Earth’s rotation)Earth’s revolution around the sun is evidenced
by the apparent motion of constellations.Thus different constellations will appear in the
night sky as the seasons change. (Earth’s revolution)
Constallationconstellation - a group of stars that are
organized in a recognizable pattern.As the night goes on, constellations appear to
change positions in the sky – this is caused by the rotation of the Earth.
Measuring TimeEarth’s rotation = one day (about 24 hours)Earth’s revolution = one year (about 365 ¼ days)
Moon’s revolution = 29.5 dayscalendar - a system created for measuring long
intervals of time by dividing time into periods of days, weeks, months, and years.
Question: Why do we have a leap year?Since a year has an extra ¼ day, every 4 years we
add a day to the month of FebruaryWho revised the calendar to account for the extra
day every four years? – Julius Ceaser
Measuring Time con’t.The modern calendar was created by Pope Gregory
XIII – much like the acient ROMANSTime Zone – 24 different time zones. The zone to
the east is an hour later than the zone on the west.Each time zone is about 15 degrees apart
International Date LineInternational Date Line was established to prevent
confusion about the point on Earth’s surface where the date changes.
The line runs from north to south through the Pacific Ocean. The line is drawn so that it does not cut through islands or continents.
Measuring Time con’t.Daylight Savings Time - Because of the tilt
of Earth’s axis, daylight time is shorter in the winter months than in the summer months
Season’sEarth’s axis is tilted at 23.5˚.Question?? Earth’s axis always points
towards what?? – North StarChanges in the angle at which the sun’s
rays strike Earth’s surface cause the seasons.
Equinoxesequinox the moment when the sun
appears to cross the celestial equator- at an equinox, the sun’s rays hit the Earth’s
equator at a 90 degree angle.Night and day light are appx. Equal
everywhere on Earth.
The autumnal equinox occurs September of each year and marks the beginning of fall in the Northern Hemisphere.
The vernal equinox occurs on March 21 or 22 of each year and marks the beginning of spring in the Northern Hemisphere.
The Season’s con’tsolstice the point at which the sun is as far
north or as far south of the equator as possible
The summer solstice occurs on June 21 or 22 of each year and marks the beginning of summer in the Northern Hemisphere.Most daylight in the summer solstice!!!!
The winter solstice occurs on December 21 or 22 of each year and marks the beginning of winter in the Northern Hemisphere.