Transcript Lunar eclipse

Warm-up
- Take out your science notebooks.
- In the notes section, on a blank sheet of paper complete the
following activity.
- Draw the diagram. Fill in the correct phases of
the moon as seen from earth. Label each phase.
Sun
Earth
Eclipses
and Tides
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http://solarsystem.nasa.gov/multimedia/gallery/Earth_Moon.jpg
Intro
• The Moon orbits at an angle with
respect to the Earth’s orbit around
the Sun.
Ecliptic plane
Moon’s orbital plane
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Eclipses
• Two kinds: Solar and Lunar
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Vocabulary
Umbra - is the innermost and darkest part of a shadow, where
the light source is completely blocked. An observer in the umbra
experiences a total eclipse.
Penumbra -is the region in which only a portion of the light
source is blocked. An observer in the penumbra experiences a
partial eclipse.
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Solar Eclipse
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When the Moon’s shadow covers part of Earth
Moon is in between Sun and Earth
When viewed from Earth, moon covers part or all of sun
Only happens at New Moon
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Total Solar Eclipse
• Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can
see the corona
• Those in “penumbra” see a partial eclipse—not safe to look directly at Sun
• Only lasts a few minutes
• Path of Totality about 10,000 miles long, only 100 miles wide
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Photo of a Total Eclipse
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http://sunearthday.nasa.gov/2006/multimedia/gal_008.php
Upcoming Solar Eclipses
• May 10, 2013, annular eclipse—not visible in USA
• Next Total Solar Eclipse in continental USA—August 21, 2017
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Eclipses
• Lunar eclipse: A lunar eclipse occurs when the
moon passes through the shadow of the earth.
• Can be partial or full eclipse
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When the Earth’s shadow covers the Moon, we have a lunar eclipse
Why is the Moon red during an
eclipse?
• The Earth’s atmosphere filters some sunlight and allows it to
reach the Moon’s surface
• The blue light is removed—scattered down to make a blue sky
over those in daytime
• Remaining light is red or orange
• Some of this remaining light is bent or refracted so that a
small fraction of it reaches the Moon
• Exact appearance depends on dust and clouds in the Earth’s
atmosphere
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Upcoming Lunar Eclipses
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Apr. 25, 2013, Partial eclipse (not visible in US)
May 25, 2013, Penumbral eclipse
Oct. 18, 2013, Penumbral eclipse
Apr 15, 2014, TOTAL ECLIPSE –visible here
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Sun
Earth
Moon
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Tides
• Tides: alternating rise and fall in sea
level produced by …
gravity of the moon.
• In one day:
• 2 high tides, 2 low tides
• The Moon’s gravity tugs on the Earth.
• It pulls the most on the part of Earth
closest, which raises the oceans.
• It pulls the least on the part of Earth
that’s farthest, which allows the oceans
and atmosphere to be further from the
Moon (and higher)
• The Sun’s gravity does the same thing,
but to a lesser extent.
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Season Vocabulary
•Seasons – A pattern of temperature
changes & other weather trends over a
year.
Season Vocabulary
• Equator –
• Imaginary line which separates the Northern from the Southern
Hemisphere
• Earth rotates around an imaginary line running through its
center called an
• axis of rotation.
• The ends of the axis are the north and south poles.
• Earth turns on its axis once in 24 hours.
• Earth’s rotation is reason for day & night
• The Earth is tilted at about a 23 ½ degree angle from its
orbit around the Sun.
• Reason for the seasons:
• Earth’s tilted axis and orbit
Season Vocabulary
• A revolution is the motion of one object around
another once.
• It takes one year for Earth to make one revolution around
the Sun or 365 ¼ days.
• Leap year every 4 years – add up ¼ days
• A rotation is one complete spin or turn on an axis.
• One rotation takes 24 hours.
Season Vocabulary
• Solstice –
• Period of time when one hemisphere gets its maximum area of
sunlight, while the other hemisphere gets its minimum amount; the
time of year when days are either longest or shortest and the angle
of sunlight reaches its maximum or minimum.
• Winter & Summer Solstice– usually 21st of December and June
• Winter: Earth is closest to the sun in December but Northern Hemisphere is
tilted away – colder temperatures/shorter days
• Summer: Earth is furthest from the sun in June but Northern Hemisphere is
tilted toward the sun – hotter temps/longer days
• Equinox –
• Period of time in an orbit in which sunlight shines
equally on the Northern Hemisphere and the
Southern Hemisphere; a time of year when
daylight and darkness are nearly equal for most of
the Earth. (Happens twice a year). Spring & Fall –
March & September
Date & Time of Solstices &
Equinoxes in 2013
Equinoxes:
March 20 2013 11:02
Solstices:
June 21 2013 05:04
September 22 2013 20:44
December 21 2013 17:11
Planet Vocabulary
• Nebular Theory –our solar system developed from cloud of dust
and gas
• Inner or rocky planets - Terrestrial
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Cratered
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Volcanism
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Closer to sun – gasses burned away
• Outer planets
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Gas giants
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Called Jovian planets
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• Distance is measured in miles, kilometers and astronomical units
(abbreviated as AU = distance from Earth to the sun or
93,000,000 miles which equals 1 AU)
• Rotation – some have a retrograde rotation which means it spins
backwards from all the other planets rotations
• Revolution – time it takes to orbit once around another object
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• Ellipse – elongated oval shape
• Temperature – measured in Fahrenheit, Celsius and Kelvin
• Greenhouse effect – trapping of gasses which doesn’t allow heat
to escape – temperatures are extreme
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• Meteoroids, meteors & meteorites – chunks of
rock & metals – range in size – called a meteoroid
when in space, meteor when it enters Earth’s
atmosphere and a meteorite when it hits Earth’s
surface
• Asteroid – Large chunks of rock and various metals
– range in size from a baseball to house-sized to
almost dwarf planet size (Ceres is over 500 miles
long)
• Asteroid Belt which is an areas that is in between
Mars and Jupiter
• Comets – called dirty snowballs – made up of ice,
dust & rock. Have an orbit that they follow. Very
elliptical. Oort Cloud as well as Kupier Belt contain
millions of comets.
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