Topic 3 and 4: Astronomy

Rotation - spinning of Earth on its axis - causes day and night - 1 day: 23 hours 56 min 4 sec - apparent motion of the sun around the earth - 15 degrees per hour

Evidence of Rotation Coriolis effect – Causes deflection of winds and ocean currents – Deflects to the right in the Northern Hemisphere – Circumpolar stars – Star trails

Foucault Pendulum

RLk coriolis RLk 9K8 pendulum 9K8 _Q0 cms _Q0

Questions 1-8

Revolution Earth moving in its orbit around the Sun Takes 1 year ( days) Moves approximately 1 degree per day Causes the seasons

Evidence of Revolution The location of the constellations in relationship to Polaris changes from month to month

Locating objects in the sky Celestial sphere: imaginary dome surrounding Earth Celestial objects: objects on the celestial sphere (sun, stars, moon, planets) Zenith: the point located directly overhead of an observer (altitude of 90 degrees)

Locating objects in the sky Altitude: the height above Earth’s surface – Celestial objects are measured in degrees – Ex: the altitude of Polaris

Azimuth: the angular measurement around Earth’s surface – Measured in degrees starting with due North located at 0 degrees Azimuth and moving clockwise around the horizon.

Direct ray of the sun Also known as the Sun’s vertical ray Occurs when the sun is directly overhead (at the zenith) NEVER occurs in New York State

Direct ray of the sun

Question 1-5 page 253

Pg 255

Pg 255 continued… Hours of daylight Characteristics wkst

Angle of insolation

Angle of Insolation Look for the direct ray – If it is over the equator----eqinox – If it is over the tropic of caNcer----summer solstice – If it is over the tropic of capricorn---winter solstice

Causes for the seasons Tilt of Earth’s axis: 23.5 degrees – The tilt causes different latitudes to have different amounts of daylight – More daylight hours means warmer temperatures in that location

What happens if we change the tilt? How does the temperature change with different tilts?

Duration of insolation wkst

Causes for the seasons cont. Revolution around the sun – Earths orbit around the sun

Causes for the seasons Parallelism of Earth’s axis: – Earth’s axis does not change direction – Ex: Summer in the Northern Hemisphere, North pole is tilted towards the sun

Altitude of the Noon Sun and path through the sky Solar noon: – When the sun has reached its highest point in the sky – NEVER directly overhead in NY

Altitude of the Noon sun and path through the sky Shadow: – Longer when sun is lower in sky – Direction at noon depends on your latitude

Where the Sun’s rays are at the beginning of each season

When the sun is directly overhead at the Tropic of CaNcer (23.5 degrees N) it is the summer solstice

When the Sun is directly overhead at the Equator, it is either the Autumnal Equinox or the Vernal Equinox

When the Sun is directly overhead at the Tropic of Capricorn (23.5 degrees S), it is the Winter Solstice

Noon Sun Angle

During an equinox: – The noon sun angle is the complementary angle to the observers latitude – Complementary angle = ? – If the observer is at 45 degrees… – 50 degrees….

Is the sun higher in the sky during summer or lower in the sky? By how much?

During the summer solstice: – Complementary angle to the observers latitude degrees

Is the sun higher in the sky or lower in the sky during winter? How much?

During a winter solstice: – Find the complementary angle to the observer’s latitude degrees

Noon Sun angle calculations Latitude: 35 degrees North – Fall equinox: – Spring equinox: – Summer Solstice: – Winter Solstice:

Noon Sun angle calculations Latitude: 40 degrees North – Fall equinox: – Spring equinox: – Summer solstice: – Winter solstice:

Noon sun angle worksheet

Solar System Models Geocentric Model: Earth Centered Explained the following: – Earth was stationary with the sun, moon and planets revolving around it – Night and day – Revolution of the moon

Geocentric model cont. Did not easily explain the following: – Movement of the inner and outer planets

Solar System models cont. Heliocentric model: sun centered Explained the following: – Places the sun in the center of the solar system – Day and night – Seasons – Motion of all celestial objects

Solar System Models

Solar System models

Solar System Models

Direction of Rotation and Revolution Earth rotates from west to east Earth revolves in a counter clockwise direction

Retrograde Motion

Apparent Diameter Change

Star trails wVfk wVfk

Constellations Random patterns of stars in the night sky Difference constellations are visible at different times of the year The big dipper is always visible in the northern sky of NY Evidence of revolution

Shape of Orbit Shape of Earth’s orbit: slightly elliptical with the sun at one foci Eccentricity: how oval an orbit is. How out of round it is

Eccentricity Calculations

The Force of Gravity Gravity: invisible of attraction Gravity depends on mass and distance The larger the mass, the greater the gravitational attraction The closer the objects are together, the greater the attraction

Planet Velocities and Area Equal area Equal time animation Fabric of cosmos clip

Distance of planets with respect to the Sun Perihelion: closest to the sun Aphelion: farthest point from the sun

Kepler’s 3 laws 1 st law: the path of the planets around the sun is elliptical in shape with the sun being located at one focus

Kepler’s three laws 2 nd law: equal areas in equal intervals of time

Equal areas Equal Time

Kepler’s 3 laws 3 rd law: the farther a planet is from the sun, the longer it takes to complete its orbit around the sun

Satellites Satellite: any object moving in an orbit around another object

Phases of the Moon The apparent shape of the moon depends on the changing positions of the sun, earth, and moon One complete orbit of the moon around earth takes 27 1/3 days. One complete cycle of the moon’s phases takes 29.5 days.

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.

unar/why_phases.gif

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

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

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

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

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

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

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

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

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

Waxing & Waning

Eclipses of the Moon and Sun Penumbra: the lighter part of a shadow “partial shadow” Umbra: the darkest part of a shadow

Lunar eclipse Occurs when the moon is in the full moon phase The moon moves into earth’s shadow Earth’s shadow is so large it may last for an hour or more (until the moon moves out of Earth’s shadow)

Solar Eclipse Occurs when the moon is in the new moon phase The moons shadow moves over Earth’s surface The eclipse occurs where the point of the shadow hits Earth’s surface

Path of Totality

Tides The rising and falling of the ocean surface Change in tide is result of the changing positions of the moon and sun relative to earth 2 high tides and 2 low tides per day

Spring Tide Occurs when the moon and Earth are aligned in a straight line with sun Occur twice a month It is the highest of the high tide and lowest of the low tide Greatest change from high to low tide

Neap Tide Occurs when the moon and Earth are at a right angle with the sun Occur twice a month It is the lowest of the high tides and the highest of the low tide Smallest change between high and low tide

Our solar system Terrestrial planets: rocky planets- primarily composed of silicate rocks – Examples: mercury, venus, earth, mars Jovian Planets: gas giants, very low density -Examples: jupiter, saturn, uranus, neptune

Size comparison video

Asteroid belt: located between mars and jupiter – Is composed of thousands of asteroids – Meteor: a streak of light in the sky that occurs when a meteoroid enters Earth’s atmosphere “shooting star”

Meteorite: meteor that reaches Earth’s surface Comets: a dirty ice ball that revolves around the sun – When close enough to the sun, exhibits a tail

How a comet really travels through space…

Galaxy Galaxy: a huge system that includes billions of stars, planets, moons and all other space matter that is held together by gravitational attraction Our galaxy: Milky Way Type: Spiral

The universe The universe: includes everything that exists from the smallest object to the largest galaxy

Big bang theory: about 15 billion years ago an massive explosion took place and started the formation of the universe – Evidence: the universe is still expanding in every direction. Radioactive aftermath of the initial explosion (background radiation) Red shift galaxies

Spectral Lines The separation of different colors based on wavelengths

Doppler Effect Red Shift: objects moving away – Caused by the expansion of space – The farther away an object moves the more the wavelength is stretched out

Doppler Effect Blue shift: objects moving towards another object – The closer object moves the more the wavelength is decreased.

Doppler shift

A star is born Nebula- cloud of dust hydrogen and plasma  Protostar  Massive star (high mass)  super red giant  super nova  blackhole or neutron star Nebula  Protostar  Main Sequence star(low mass)  Red giant  planetary nebula  white dwarf

A star is born Star formation: stars start out in a nebula which is a massive cloud of dust, hydrogen, and plasma. Due to gravitational attraction the cloud collapses and the temperature increases significantly  Nuclear fusion starts with hydrogen becoming helium A protostar forms and depending on mass the star will either become a massive star or a main sequence star

Star formation video

HR diagram