Science 9

Unit 1: Space

Chapter 10: What we know about the universe has taken us thousand of yearsCelestial Body: a natural object out in space such as a planet, a moon, an asteroid, a comet, or a star

Two types of Celestial Bodies:

1. Star: like our sun, give off heat and light and are thousands of years away.

2. Planets: a celestial body that orbits one or more stars, is large enough that its own gravity holds it in a spherical shape, and is the only body occupying the orbital path.

Constellations: a distinctive pattern in the night sky formed by a group of stars. It often looks like a familiar object like an animal.

Examples:

Ursa Major or the great bear

Ursa Minor or the little bear

Orion the hunter

Cassiopeia the queen

Leo the lion.

Motion of the Planets

They follow an ecliptic path called orbits around the Sun. The orbits are like long, slightly flattened circles.

The planets move at different rates due to their distance from the Sun.

These orbits result from gravitational forces

As the Earth revolves around the Sun, it appears that the Sun is moving against the background of stars

As the planets revolve around the Sun, they move at different rates along an ecliptic path.

Those inside Earth’s orbit (Mercury and Venus) appear to race through the sky and appear to be close to the Sun

Those beyond Earth’s orbit are slower (Mars) and appear far from the Sun in the sky. Seem to move against the background of stars in the sky

Motion of Asteroids and Comets

Both Orbit around the sun

Asteroids: one of many small rocky bodies in our solar system, most of which orbit the Sun between Mars and Jupiter.

Comet: A celestial object consisting of a nucleus of ice and dust.

The orbits of comets can be above or below the orbit of Earth, for this reason we do not always see the comet on the ecliptic.

They can orbit in different planes (unlike all other planets)

Their tails get longer as they get closer to the sun.

Motion of the Moon

The moon orbits around Earth once every 28 days

Other motion…

Planets, suns (stars) and moons spin on a central axis.

Earth spins on its axis, which is an imaginary line from the North Pole to the South Pole.

Example: the Earth spins on its axis towards the east. Stars, including the Sun, all generally move from east to west.

Early Models and Evidence About our Universe

Aristotle:

saw the universe as geocentric – the Earth at the center and the sun, moon, planets and stars revolving around it.

Patterns of stars does not change so he thought the Earth was in a fixed place

During a lunar eclipse, the shadow cast on the moon had curved edges so Earth must be a sphere.

Aristarchus

proposed that the universe was heliocentric, revolved around the sun but not widely accepted at this time

Erathosthenes of Cyene:

first person to accurately measure the diameter of Earth.

Ptolemy:

He noticed that the motion of Mars in the sky over several weeks creates a loop in the sky. This change in direction is called retrograde motion.

To explain this motion, Ptolemy proposed that each planet revolved around a point on its orbit, called an epicycle, to explain its motion through the heavens

Copernicus:

he thought the earlier observations could be explained in a simpler way by a model in which Earth rotated on its axis once daily and revolved around the Sun once a year. (Heliocentric model)

The Earth’s motion around the Sun is relatively recent (1543)

Galileo:

First person to turn a small telescope towards the sky and publicly report what he saw.

Observed craters on the moon, spots on the sun, and four “stars” orbiting Jupiter.

Galileo also observed that Venus had phases like our moon does and this could only happen if Venus orbited the Sun

Galileo published his findings and was imprisoned for his work by the Catholic church because they taught an Earth centered universe.

Johannes Kepler:

with the help of Tycho Brahe, made observations of Mars’ orbit and found that it modeled an ellipse (oval shape)

Kepler developed three laws of planetary motion

All planets move in ellipses, with the sun at the center

The speed of the planet as it revolved around the sun is not constant. Closer to the sun it speeds up

The time it takes the planet to revolve around the Sun is related to how far away it is from the Sun

Sir Isaac Newton:

developed three laws to predict and describe motion and explained how celestial bodies move through the universe.

He was the first to show mathematically that the force of gravity reaches far beyond the surface of Earth and affects all celestial bodies

This force causes the bodies to remain in orbit around larger bodies

Invented the reflecting telescope which allowed more precise observations.

Early Technologies for Observation

Stone Circles: possibly used to make simple astronomical observations. For example, Stonehenge. On midsummer’s day the Sun rises directly over a particular stone in Stonehenge. Marking the longest day of the year.

Astrolabe: around the time of Ptolemy, they were used to help locate and predict the positions of the Sun, Moon and stars

Using a compass and an astrolabe, they were able to describe the position of any celestial body in relation to the direction North as well as in relation to the horizon.

Telescope: Refracting telescope (uses lenses to gather and focus light) was used by Galileo to make his observations (Sun centered universe)

Reflecting Telescope: (uses mirrors to gather and focus light) was developed by Newton to make even more precise observations and this design is used today, called the Newtonian design

Chapter 11: We continue to learn a lot about the solar system by using space explorationThe Sun

All life on Earth is dependent on solar energy in the form of radiation. Ex: plants need it for food

Most of the Sun is made up of hydrogen. Hydrogen fuses together to create helium plus a tremendous amount of energy (heat, light etc). This is called a thermonuclear reaction.

Sun Spots:

dark patches on the Sun’s surface that are slightly cooler, about 3500°C, than surrounding areas.

The number of sunspots on the Sun may affect Earth’s climate, although it is still being debated

There are records that show a lack of sunspots during much of the 17th century, when Europe experienced a mini ice age.

Solar Flares:

Extremely violent eruptions of gas from the Sun’s surface (corona) occurs. These eruptions can last for a few hours and heat gases to 11 000 000°C.

The gas is spewed out in every direction.

Solar Wind

When these high energy particles rush past Earth they create an effect called solar wind.

Earth’s magnetic field deflects most of this dangerous solar wind

Northern & Southern Lights

• Some of it enters at the North and South pole, collide with gases in the atmosphere and create the auroras (northern and southern lights)

• The solar wind can disrupt Earth’s magnetic field, disabling satellites and even knocking out power transmission line on Earth.

Planets

Planet: a body that must orbit one or more stars, be large enough that its own gravity holds it in a spherical shape, and be the only body occupying the orbital path

Terrestrial Planets: inner, rocky planets, Mercury, Venus, Earth, and Mars

Jovian Planets: outer, gaseous planets, Jupiter, Saturn, Uranus, and Neptune

Criteria Terrestrial Planets Jovian Planets

Size Small (All Earth size or smaller) Large (4 to 11 times larger than Earth)

Motion Slow spinning, small orbits Faster spinning, large orbits

Composition Solid and rocky Gaseous

Distance from Sun Closer Further away

Temperature Warmer, but temperatures vary Colder, but temperatures vary

Density Greater Lesser

Planets…

Closer to the sun, the temperature is warmer and the composition is solid and rocky

Further from the sun, the temperatures are lower and the composition is gaseous.

Order of the planets: My Very Educated Mother Just Served Us Nachos (Mercury, Venus, Earth, Mars , Jupiter, Saturn, Uranus, Neptune)

Dwarf Planets

Dwarf Planet is a celestial body orbiting the Sun that is generally smaller than a planet but massive enough for its own gravity to give it a round shape.

They do not have enough mass and gravity to clear their orbits of smaller debris left over from the formation of the solar system. Ex. Pluto, Eris and Ceres

Asteroids

Asteroids are smaller bodies that are believed to be leftover remains of the formation of the solar system

Most orbit the sun very similar to planets

The main location for asteroids is in a band between Mars and Jupiter

Some asteroids have irregular orbits due to gravitational attraction of the planets and collisions.

Comets

Comets are often referred to a “dirty snowballs” made up of ice, rock, and gas.

They originate beyond the orbit of Neptune, at the farthest reach of the Sun’s gravitational influence.

Here lies a spherical cloud of small icy fragments of debris called the Oort cloud.

Comets are usually characterized by one or more “tails” due to a loss of dust and ice due to exposure to solar radiation (it starts to melt)

Comets & Periodicity

Comets have unique orbits around the sun and tend to follow a pattern with regards to their passage by the Earth and Sun

Two types of comets: Short and Long Period comets. Short period comets orbit the Sun faster.

Periodicity: How long it takes a comet to orbit the sun

Meteoroids: are pieces of rock floating through space

Meteors: (“shooting stars”) are meteoroids that burn up as they enter Earth’s atmosphere at high speed

Meteorites: meteors that are large enough to survive passing through the atmosphere and they reach Earth’s surface.

Criteria Asteroid Meteor Meteorite

Size Sand grains to about 1000 km across

Sand grains Larger than meteor

Composition Pieces of Rock Pieces of Rock Pieces of Rock

Location Mainly the Asteroid belt (between Mars and Jupiter)

Earth’s Atmosphere On Earth

When meteorites hit earth?

Impact sites: the place where a relatively small object (meteorite) has collided with a large object (planet) to produce a fairly circular depression on the surface of the larger object.

Often referred to as an impact crater due to the circular depression that was formed

Impact sites provide evidence of meteor/asteroid impacts on a planet

The size of the depression created is often much larger than the object involved in the collision.

Canadian Contributions to Space

Canadarm 1: robotic arm used to retrieve and launch many satellites and to give a stable platform for astronauts going about their tasks in space

Canadarm 2: a mobile remote manipulator system designed for the International Space station. Able to do everything Canadarm 1 does but larger and able to move by itself to nearly every part of the station

Dexterous manipulator of Canadahand: a two armed robot that attaches to the end of Canadarm 2. Performs task that previously required astronauts to work outside the safety of the space station.

International Space Station: Sixteen countries including Canada are involved in this space based laboratory.

Canadian Astronauts

Chris Hadfield Roberta Bondar Marc Garneau Julie Payette

Technologies that have increased knowledge of the Universe

Hubble Space Telescope: Placed in Earth’s orbit and with no air (pollution etc.) to spoil the view, this has given amazing views of far away galaxies and stars in space

Using this they were able to find that the universe is between 13 and 14 billion years old

Light reaching its mirrors has not been distorted by Earth’s atmosphere

The Very Large Array Radio Telescope: Made up of 27 antennas that are each 25 m across. The result is the same as one giant radio telescope that is 36 Km wide

Radio telescope reveals characteristics of celestial bodies that could not be studied using optical telescopes like the previous two telescopes

Dust in space makes it difficult to see light from distant stars but this telescope is not affected by dust (uses radio waves). Using this, we get a clearer picture.

Spectroscopy: A spectroscope is an optical instrument that acts like a prism to separate light into its basic component colors (a spectral pattern).

– This allows astronomers to view the spectral pattern produced by individual stars.

– Spectral lines stand out across the bands of color in a star’s spectrum

– The dark lines tell you the wavelength of the visible light given off by a star

– Tells about the types of atoms giving off light, and used to determine what the star is made up of

Adaptive Optics

– With Earth based telescopes the view can be distorted by the Earth’s atmosphere (so stars appear to twinkle)

– Telescopes can now be made with mirrors to overcome this distortion. This design is called adaptive optics

– A computer monitors the atmosphere while the telescope is being used and small mechanisms slightly change the shape of the mirror to compensate for this distortion

Rocket is a system used for transporting materials and astronauts into space.

– Filled with explosive fuels (chemistry)that combine to generate thrust, the force (physics) that pushes against the rocket to get it to move

– As fuel is used up, some of the rocket is lost to make it lighter

Space Suits: acts as a smaller space ship, providing oxygen to breathe

– Contain a communication system to talk to each other and people on Earth (radio waves, physics) a cooling system and a system to simulate the air pressure on Earth’s Surface (air pressure, physics)

Satellites are electronic devices put in orbit around Earth to relay information.

– Communications satellites use electromagnetic radiation is used to send information from one place to another (involves physics)

Rovers: are small movable probes designed to land on a planet, explore and test the surface and send the information back to Earth by radio waves.

– They conduct experiments in geology (determining the make up of rocks) and biology (looking for signs of life)

Optical telescopes: use the property of light (physics) to get a better picture of the universe.

– Hubble space telescope is in Earth’s orbit. This also uses electromagnetic waves from the field of physics to send information back to Earth.

Radio Telescopes: Radio signals coming from distant objects are collected and converted to electrical symbols and analyzed.

Chapter 12: We can use space exploration to learn about stars, nebulae, and galaxies outside our solar systemEarly ideas…

100 years ago, you would have been told that things never change in space

New evidence has caused scientists to rethink existing theories. Between 1918 and 1929 more powerful telescopes were developed and more celestial bodies were seen.

Edwin Hubble

The first astronomer to identify other galaxies besides the milky way.

Galaxy: a collection of stars, planets, gas and dust held together by gravity

He estimated the distance from Earth to 46 galaxies

He noticed that all of the galaxies he was observing were moving away from each other

He proposed that the universe is expanding in all direction.

Universe: The huge space which contains all of the matter and energy in existence.

Hubble used Red Shift analysis, using spectroscopy, to explain how the universe is expanding

The light that leaves a distant galaxy travels an enormous distance through space before reaching a telescope.

When a galaxy first emitted its electromagnetic waves they were not red shifted (or made longer)

Only as space expanded did it cause the waves to lengthen and become red shifted

This shows that the light’s wavelengths are becoming longer It indicates that the object is moving away from us.

This was observed with many galaxies so the idea that space itself must be expanding was developed.

Red Shift Analysis

A shifting of light from an object toward the red (longer wavelength) end of the spectrum as the object move away from earth.

The Big Bang Theory

Big Bang Theory: Theory about the origin and evolution of the universe Suggests that because of the evidence we have for an expanding universe, the

universe must have been more compact at an earlier time. They traced the paths backwards.

Estimate that the present matter in the universe was compressed together into a hot, dense mass 13.7 billion years ago.

This matter began to move outward after a massive explosion

Oscillating Theory

Oscillating Theory: Suggest that the universe will expand to a certain point in time

Then, due to forces of gravitation among the stars and galaxies, contract

Scientists believe this will result in a “big crunch” followed by another Big Bang

Like a bungee jumper: when they jump they accelerate due to gravity but eventually the force of the bungee will pull the jumper back.

The Solar System

Solar System: The sun together with the eight planets and all other celestial bodies that orbit the sun.

Nebulae

Nebulae: In between the stars in a galaxy, there are clouds of hydrogen gas and dust called Nebulae.

If material in these clouds can be pulled together stars can form.

When a star forms its hot core remains surrounded by gas and dust and this leftover material can collapse and further collisions with other materials can occur eventually making a planet.

Nebular Hypothesis: the sun and the planets formed when a large nebula condensed and collected together by gravity

Stellar Collision Theory

Stellar Collision Theory: a theory that suggests that our Sun and the planets were created from collisions between stars.

The Nubular Hypothesis is believed to be more likely from observation of other star systems.

Light Year

Light year: The distance that light, which moves at 300 000 km/s, travels in a year; equals 9.5 trillion Km.

Light Year is a unit of measurement for extremely large distances. It is not a unit of time but a unit of distance.

The light from the moon takes 1.3 seconds to reach us so you are seeing the moon as it was 1.3 seconds ago.

The light from Jupiter takes 41 minutes to reach us, so you see Jupiter as it was 41 minutes ago.

When you look at objects far away in space, you are looking back in time

Major Parts of the Universe

Interstellar matter: made up of gas (mostly hydrogen) and a small amount of dust

Nebulae: clouds of dust and gas

Galaxy: forms when gravity causes a large, slowly spinning cloud of gases, dust and stars to contract. All the stars in the universe were formed in galaxies.

Three types of galaxies:

1. Elliptical Galaxies

A galaxy that ranges in shape from a perfect sphere to an elongated but flattened ellipse and contains some of the oldest star in the universe.

2. Spiral Galaxies

A shape for a galaxy with many long “arms” spiraling out from a center core made up of stars that formed long ago.

3. Irregular Galaxies

A galaxy that has neither spiral arms nor an obvious central core, made up of a mix of newly forming stars and old stars.

Black Holes

a large sphere of incredibly tightly packed material with an extraordinary amount of gravitational pull created when a star collapses into itself. It is called a black hole because nothing, not even light, can escape the powerful gravitational field.

Forms from a star 25 times the size of the sun.

Quasars:

A region of extremely high electromagnetic energy that develops as the super massive black hole in the center of a galaxy attracts more matter into itself.

Star: an object in space made up of hot gases, with a core that is like a thermonuclear reactor. There are giant and dwarf stars.

Dwarf Star: low mass stars that start small and stay that way most of their life. Burn hydrogen fuel slowly and have long life

Giant Star: Those stars that have the mass of the sun or greater. Burn hydrogen fuel faster and have a shorter life.

Birth of a Star

Begins to form from the materials in a nebula Gravity acts on chunks of gas and dust, pulling them together Gravity keeps working and the mass grows, materials collapses on itself

and contracts, now called a protostar (early star)

Collects more mass, temperature of the core becomes very hot, atoms fuse together to form larger atoms

Hydrogen atoms combine to from helium and this process called nuclear fusion creates a lot of energy and it is released and the star glows.

Three possible lifecycles of stars: (pg. 447-448)

Low Mass Stars Intermediate Mass Stars High Mass Stars

Careers Associated with Space:

Astronauts Scientists – astronomers, physicists Engineers – electrical Doctors Pilots Technicians - lens makers

Benefits and/or consequences of Space Exploration

Medical: Astronauts experience bone density loss. Help to study Osteoporosis

Industrial: great deal of technology invented for space exploration is being used everyday. Ex. Cold weather clothing

Agricultural: freeze dried food was invented for space travel but has spilled over in everyday life

Meteorological: View hurricanes, storms from space to help study them Military: Observation of other countries