Overview of the solar system

Solar system includes • Sun• Eight planets and their satellites• Three Dwarf Planets• Asteroids• Comets• Meteoroids

The Planets

Add the SUN

How Small Are WE?

AsteroidsAsteroids

Most lie between Mars and Jupiter• Microplanets: small, rocky bodies• Irregular shapes

CometsComets

• Large, "dirty snowballs"• Composition:

•Frozen gases•Rocky and metallic materials

• Produces a glowing head called the coma and a tail that points away from the sun

Comet Hale-Bopp

MeteoroidsMeteoroids

• Meteoroid – small solid particle that travels through space

• Meteor – when a meteoroid enters Earth’s atmosphere, “shooting star”

• Meteorite – when a meteoroid reaches the Earth’s surface

Which one of these is not like the others?

RIGHT! Pluto does not belong…

WHY?The resolution

The decision establishes three main categories of objects in our solar system.

• Planets: The eight worlds starting with Mercury and moving out to Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

• Dwarf planets: Pluto and any other round object that "has not cleared the neighborhood around its orbit, and is not a satellite."

• Small solar system bodies: All other objects orbiting the sun.

Early History of AstronomyEarly History of Astronomy

Astronomy: the study of the universeAncient astronomy:• Ancient Greeks – Golden Age of early

astronomy• Used geometry and trigonometry to measure

sizes and distances of the sun and moon• Aristotle – the Earth is round• Geocentric model– Earth is the center

Early History of AstronomyEarly History of Astronomy

Birth of modern astronomy • 1500s and 1600s• Five noted scientists

1. Nicolaus Copernicus (1473-1543)• Concluded Earth was a planet• Heliocentric model – Sun is the center

Early History of AstronomyEarly History of Astronomy

2. Tycho Brahe (1546-1601) • Made most precise observations yet

which were used by other astronomers

Early History of AstronomyEarly History of Astronomy

3. Johannes Kepler (1571-1630) • Planets revolve around the Sun• Three laws of planetary motion

Early History of AstronomyEarly History of Astronomy

4. Galileo Galilei (1564-1642) • Constructed a telescope and saw the

universe in a new way• Discovered:

• Four moons of Jupiter• Planets appeared as disks• Phases of Venus• Features on the Moon• Sunspots

Early History of AstronomyEarly History of Astronomy

5. Sir Isaac Newton (1643-1727)• Law of universal gravitation• Explained planetary motion

TELESCOPESTELESCOPES

• Tools used to help astronomers see celestial (space) objects with greater detail by:– gathering more light than your eye can

(dim objects are easily seen)–magnifying images to separate distant

objects from one another

Hubble space telescope• Over 350 miles from earth

Hubble Space Telescope Size:Length: 43.5 ft (13.2 m)Weight: 24,500 lb (11,110 kg)Maximum Diameter: 14 ft (4.2 m)Hubble is nearly the size of a large school bus—but it can fit inside a space shuttle cargo bay.

Hubble found that galaxies are speeding away from each other, consistent with a general expansion of the Universe.

This is called the Big Bang.

Deep Space Image

Optical TelescopesOptical Telescopes

• use lenses and mirrors to collect starlight and light reflected off of planets

• Two main types:– Refracting – simple refractors uses two lenses.

One lens collects the light, and the other magnifies the image.

– Reflecting – uses a large curved mirror to gather and focus the light. Another lens magnifies the image.

REFRACTING – SIMPLE OPTICAL TELESCOPEREFRACTING – SIMPLE OPTICAL TELESCOPE

REFLECTING – ADVANCED OPTICAL TELESCOPEREFLECTING – ADVANCED OPTICAL TELESCOPE

Optical Telescopes

Keck TelescopesSummit view of the twin Keck telescopes, located at 13,600 atop a dormant

volcano in Hawaii.

Kepler’s Laws

1.) The Law of Ellipses-The Path of the

planets about the sun is elliptical in shape, with the center of the sun being located at one focus.

Kepler’s Laws2.) The Law of Equal Areas

- An imaginary line drawn from the center of the sun to the center of each planet will sweep out equal areas in equal intervals of time.

Kepler’s Laws

3.) The law of harmonies- Compares the orbital period and radius of

orbit of a planet to those of other planets.

Astrophotography

The Way We Move

• Rotation• Revolution• Procession• Tilt• Nutation• Barycenter

What is Rotation

The turning or spinning of a body on its axis.

Earth’s RotationThe average rotation period of the Earth with respect to the Sun is 24 hours (the mean solar day).

What is Revolution

The motion of a body along a path around some point in space.

This is also called Orbital Motion

Earth’s Revolution

It is the orbital period of Earth, equal to 365.25636042 mean solar days.

What is Precession

The slight movement of Earth’s axis over 26,000 years.

Diurnal motion of stars

• We cannot detect earth’s rotation, so it appears to us as if the stars (and Sun and Moon and planets) are rotating around us: they rise in the east and set in the west, once a day.

This is called diurnal motion.

Tilt of earth on axis

A few more ways to move

• Nutation –the wobble– Change in the angle of the axis (1/2 degree)

• Barycenter– The point between two objects where they

balance each other. – Spin demonstration

Life cycle of stars.

The lifespan of stars varies from thousands of years for massive stars to billions for smaller stars. Our Sun, which is of average mass, is predicted to live for about 10 billion years (it is about halfway through).

Hertzsprung - Russell Diagram

Tilt of earth on axis

Special days of the year

• Winter Solstice first day of winter, shortest day of the year

• Vernal Equinox first day of spring, equal day and night

• Summer Solstice first day of summer, longest day of the year

• Autumnal Equinox first day of autumn (fall), equal day and night

Seasons

Definition

• One of the four periods of the year (spring, summer, autumn, and winter), beginning astronomically at an equinox or solstice, but geographically at different dates in different climates.

Spring

• Begins on the vernal equinox• Usually occurs on March 21 or 22 in the

northern hemisphere• Tilt neither toward nor away from sun• Equal day and Night

Summer

• Begins on the summer solstice • Usually occurs on June 21 or 22 in the

northern hemisphere• Tilt toward the sun• Longest day of the year

Fall

• Begins on the autumnal equinox• Usually occurs on September 22 or 23 in the

northern hemisphere• Tilt neither toward nor away from sun• Equal day and night

Winter

• Begins on the winter solstice• Usually occurs on December 21 or 22 in the

northern hemisphere• Tilt away from sun• Shortest day of the year

What causes seasons• TILT! Either toward or away from the sun.

• Tilt TOWARD the sun is maximized during Northern Hemisphere summer in late June (the "summer solstice"). – The amount of sunlight reaching the Northern Hemisphere is at a

maximum. • Tilt AWAY from the sun is maximized during Northern

Hemisphere winter in December (the “winter solstice").– a minimum of sunlight reaches the Northern Hemisphere.

• The seasons are reversed in the Southern Hemisphere

Interesting facts• The sun is actually closest to the Earth during

Northern Hemisphere winter (not summer). • Because of this, the amount of sunlight averaged

over the whole Earth, is as much as 7% more intense in the winter than the summer.

• Despite this fact, the global-average surface temperature is warmer in Northern Hemisphere summer, due to the much greater expanse of land there, and since land heats to a higher temperature than the ocean does.

Life cycle of stars.

The lifespan of stars varies from thousands of years for massive stars to billions for smaller stars. Our Sun, which is of average mass, is predicted to live for about 10 billion years (it is about halfway through).

Hertzsprung - Russell Diagram

Energy from the Sun

Essential Question: How does the sun produce energy, and

how does the energy reach earth?

Layers of the Sun• Interior – cannot be seen– where energy is produced

• Photosphere – Photo =“light” Sphere = “ball” – visible “surface” of the sun

• Atmospheric layers– Chromosphere – thin layer of hot gases– Corona – “crown” outermost portion, produces

the solar wind• Earth’s magnetic field blocks the winds from reaching

our surface

Production of Energy

• Combustion – burning fossil fuels• Renewable Sources – capture energy from the

sun, wind, water to produce electricity

• Nuclear Reactions – when atomic particles interact to form different particles– Fusion – Fission

Fusion

• Done in the interior of the sun

• Less massive nuclei combine to form more massive nuclei

• Releases lots and lots of energy

Fission

• Able to do on earth (Nuclear Energy)• More massive nuclei are bombarded by

neutrons and split to less massive nuclei• Emits heat energy

Energy Flow

• Energy is transferred by Electromagnetic Radiation

• This includes all energy types that travel as waves from X-rays to visible light to microwaves and radio waves

Forms of Energy Produced

• Light – acts like a wave and particle– photons are a stream of particles that push on

matter– This push is what causes a comet’s tail

• Heat– The sun is extremely hot (15 million K at core)– Waves of heat are ejected into space at all angles

Life cycle of stars.

The lifespan of stars varies from thousands of years for massive stars to billions for smaller stars. Our Sun, which is of average mass, is predicted to live for about 10 billion years (it is about halfway through).

Hertzsprung - Russell Diagram