(c) mcgraw hill ryerson 2007 10.1 the early universe until 100 years ago, scientists believed...

(c) McGraw Hill Ryerson 2007

10.1 The Early Universe

• Until 100 years ago, scientists believed nothing ever changed in outer space.

• Using powerful telescopes, astronomers like Edwin Hubble discovered many new celestial bodies, and observed that everything in the universe was moving further apart.

• The universe expands like baking bread; galaxies and other celestial objects are like raisins in the dough, moving apart as the bread bakes.

See pages 346 - 347


Red Shift Analysis

• By examining the light from distant stars, astronomers can estimate the speed and directions the star is traveling.

• Light, like all forms of electromagnetic radiation, travels in waves. Objects in space give off many different forms of radiation.

• Like the sound of a ambulance siren changes as it passes you, light from stars exhibits red-shift, indicating speed and direction of motion.

• A spectroscope analyzes the unique spectrum of a star, which astronomers can analyze to discover the direction and amount the light has shifted.

• A red shift means the wavelength is getting longer, and the star is moving away from us.

• Blue shift is the opposite; the star is getting closer.

See pages 348 - 349


The Big Bang Theory

• Once astronomers realized everything was moving away from everything else, they realized the universe might have originated from a single point.

• The Big Bang theory suggests that everything in the universe came from a single starting point, approximately 13.7 billion years ago.

See pages 350 - 352

• Although there are other theories about the beginning of the universe, much scientific evidence supports the Big Bang theory.

• The Big Band is also supported by the presence of cosmic background radiation, which is the energy left over from the Big Bang.

• This radiation was mapped by the COBE and WMAP explorations.

Take the Section 10.1 Quiz

http://www.bcscience.com/bc9/pgs/quiz_section10.1.htm


10.2 Galaxies

• Our star, the sun, is one of 100 million stars in the Milky Way galaxy - and there are 125 billion galaxies in the universe!

• A galaxy is a large group of stars. A nebula is a cloud of gas and dust in space that is often produces a new star, or is the remains of an old star.

• Galaxies can be spiral, elliptical or irregular in shape.• How fast a galaxy spins helps define its

shape.• Each galaxy has stars clustered as globular

clusters or open clusters.

See pages 356 - 360 Take the Section 10.2 Quiz



11.1 Stars

• A star is a massive sphere of gases with a core like a thermonuclear reactor.

• The most common celestial bodies in the universe are stars.

• It is estimated there are more stars in the universe than there are grains of sand on all the beaches on Earth.

• By peering through the interstellar matter (dust and gases), astronomers an observe the birth of stars.

See pages 368 - 369


The Birth and Life of Stars

• Stars form from the dust and gases found in a nebula, when enough gravity causes all the molecules to collapse in on themselves.

See pages 370 - 371

• If enough matter gathers, the gravity becomes so massive that hydrogen atoms join to form helium atoms, producing huge amounts of energy through the process of fusion.• It is the energy given off by fusion that

causes stars to glow.• The life cycle of a star: nebula, low mass

star, intermediate mass star (like our Sun), high mass star. Large high mass stars often explode as supernovas, spreading elements throughout the universe.


• Stars 12 - 15 times more massive than our Sun can end as neutron stars after going supernova. These superheated, super massive dead stars can take trillions of years to cool.

• Stars can vary greatly in size. Although our Sun is an average size, many of the stars we see in the night sky are up to 3000 times as large as the Sun.

See pages 372 - 373

• Stars 25 times as massive as our Sun can become black holes instead of neutron stars. The same process that produces a neutron star produces an area so massive and yet so small that the gravity it produces traps everything - even light!


The Hertzsprung-Russell Diagram

• By studying stars, astronomers have have created an evolutionary ‘lifespan’ that stars progress through.

See page 374

• The Hertzsprung-Russell diagram was developed to show the different stages of a star’s life.

• 90% of stars are in the main sequence, where energy is produced combining hydrogen atoms into helium.

Blue Red


Analyzing Star Colour

• The colour of a star reveals its temperature and composition to astronomers.

• Red stars = cool = 3000 ºCYellow stars = hot = 6000 ºCBlue stars = hottest = 20 000 ºC - 35 000 ºC

• Using a spectroscope, the light emitting from a star reveals spectral bands that show certain gases in the star.• Of course, spectral lines are also used to identify the movement of stars by

utilizing red-shift analysis.• Red-shift is an example of the Doppler effect, which states that as a wave-

emitting object moves, the wavelength of its waves change.

See pages 374 - 375


Colour and Motion

• The Doppler effect refers to the way waves either compress as their source gets closer, or lengthen as the source gets farther away.• The unique spectral pattern each star reveals when examined through a

spectroscope allows astronomers to see if the lines shift towards the red part of the spectrum (moving away) or blue (moving closer).




11.2 The Sun and the Planets

• Our Sun, an average star in the universe, is the center of our solar system.

• Our solar system is full of planets, moons, asteroids and comets, all of which revolve around the Sun at the center.

• When a star forms from a nebula, gravity pulls most of the material into the new star, but some may also clump together to form objects in a solar system.• A planet is a celestial body that orbits one or more stars.• Each planet may also spin on its axis (rotates) while it orbits the Sun (revolves).

• Our solar system formed approximately 4.5 billion years ago. The four inner, rocky planets in the first 100 million years on the Sun’s existence, while the outer, gaseous planets formed later from the remnants of the Sun’s original nebula.

See pages 382 - 383


The Sun

• The Sun contains 99% of all the mass found in our solar system.

• The Sun has a diameter equal to 110 Earths.• The Sun is made up mostly of hydrogen. The hydrogen molecules are forced to join together through massive gravity, forming new helium molecules, and releasing huge quantities of energy as light and heat through the process of thermonuclear fusion.

• The Sun has no solid surface, but has distinctive features such as sun spots, flares and prominences. • The photosphere is the surface of the Sun. It looks blotchy due to rising and cooling gases.• The corona is the outer portion of the Sun’s atmosphere.

See pages 383 - 384


• Sometimes, gases from the Sun’s corona erupt outwards like a bursting soap bubble.

See page 385

Solar Winds

• The resulting solar wind is full of high-energy particles that would kill any life on Earth they struck.

• Luckily, our magnetic field deflects this solar wind. We can see these particles being deflected when we see the Northern Lights.

• Large outbursts of solar winds can wreak havoc with satellites as well as Earth-bound energy supplies such as power plants.


The Planets

• To be considered a planet, a body 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.• Distances between planets in the solar system are measured in astronomical units

(AU). One AU = the average distance from the Sun to the Earth.• The inner planets are relatively close to the center of the solar system - Mars is

1.52 AU from the Sun. The next planet, Jupiter, an outer planet, is 5.27 AU from the Sun. The most distant planet, Neptune, is 30.06 AU from the Sun.

See pages 385 - 387

Inner, rocky planets Outer, gaseous planets

Mercury Smallest planet Jupiter Largest planet

Venus Earth’s sister Saturn Rings + many moons

Earth Only life in universe Uranus Methane gas planet

Mars The red planet Neptune Outermost planet


Other Solar System Bodies

• There are also numerous celestial bodies smaller than planets in our solar system.

• Moons are found around all planets except Mercury and Venus.• Asteroids are found mostly between Mars and Jupiter in the steroid belt. It is

thought these are ‘leftovers’ from the formation of the solar system.• Comets (sometimes called “dirty snowballs”) are actually rocky travelers, following

huge orbits far outside the planets in the Oort Cloud.• Trans-neptunian objects refer to objects outside Neptune’s orbit, including ex-planet

Pluto (now referred to as a dwarf planet). These objects orbit the Sun in a lagre area known as the Kuiper Belt.

• The Oort Cloud is at the farthest reaches of the Sun’s gravitational pull, almost 25% of the way to the next nearest star, Proxima Centauri.




11.3 Measuring Distances in Space

• We use AUs for distances within our solar system, and light years for distances outside our solar system.

• A light year is the distance light travels in one year = 9.5 trillion km.• Even the light from the nearest stars takes several years to reach the Earth.

The light that we see from more distant stars has taken thousands, or even millions, of years to reach the Earth.

• Astronomers use red-shift to determine motion, and can use triangulation and parallax to calculate position.• Triangulation uses geometry to estimate actual distances between objects in space.• Parallax is a method that uses changing position to provide a baseline for triangulation.

See pages 396 - 398


Techniques for Indirectly Measuring Distance

• Since it is impossible to measure actual distances in space, astronomers use mathematical methods to estimate distances.

• Triangulation uses the geometry of a triangle to find the distance to far away objects.• First, a baseline is measured. The longer the baseline, the more accurate the distance measurement will be• Next, measure the angles from each end of the baseline to the object.• Next, draw a scale diagram that represents the baseline measurement and the two angles out to the distant point.• Finally, by measuring the height of the triangle that forms, you find the distance to the object.

See pages 399 - 400Scale: 1 cm = 100 m

Baseline distance


Techniques for Indirectly Measuring Distance

• Since it is impossible to measure actual distances in space, astronomers use mathematical methods to estimate distances.

• Parallax works in a similar way to triangulation, except the baseline we use is huge - the diameter of the Earth’s revolution around the Sun!• Parallax refers to the concept that objects closer to us appear to change position compared to objects much farther away.• First, the baseline is measured. Astronomers can very accurately record the diameter of the Earth’s orbit around the Sun.• Next, measure the angles from each end of the baseline to the object. In this case, each end of the baseline will occur 6 months apart! • Next, draw a scale diagram that represents the baseline measurement and the two angles out to the distant point.• Finally, by measuring the height of the triangle that forms, you find the distance to the object.

See page 401Take the Section 11.3 Quiz



12.1 Earth, Moon and Sun Interactions

• Humans have been aware of the relationships between the Earth, Sun and Moon for thousands of years, but only recently have we began to better understand the true nature of these relationships.

• Ancient civilizations used the seasons, months, position of stars and other astronomical information in many parts of their lives.

• Until the past few hundred years, humans believed the Earth was the center of the universe (the geocentric model).• The geocentric model was based on the work of the ancient Greek

philosopher Ptolemy• We now observe the heliocentric model, where the Sun is the center of the solar

system, and the universe expands outward.• The heliocentric model is based on the observations of Copernicus and

Galileo.

See pages 410 - 411


The Moon

• Earth’s nearest neighbour in space is the Moon, a natural satellite that most likely formed from a collision between the Earth and a Mars-sized planet during the formation of the solar system.

See page 412

• The surface of the Moon, which can be seen clearly with good binoculars, is not protected by an atmosphere like the Earth’s.

• The surface of the Moon is bombarded with space debris, but also does not suffer from erosional forces like wind and water.

• Light-coloured surfaces are highlands made of very old rock, while darker surfaces are called mare, and are lower, flat stretches of basalt.


Phases of the Moon

• The Moon, reflecting light from the Sun, appears to change in size and shape as it rotates on its axis and revolves around the Earth.

• It takes the Moon 29.5 days to make a complete orbit around the Earth. During this time, different portions of the Moon can be viewed as the changing phases.• Interestingly, the Moon rotates at almost the same rate as it revolves,

meaning that the same surface of the Moon (the “near” side) always faces the Earth. The “far” side is always facing away from the Earth!

• What we see as the changing phases are actually just different viewing points of the Moon’s “daylight”, time periods when the Sun shines on the Moon.

• The Moon’s gravity pulls on the oceans on Earth to create tides.

See pages 412 - 413


The Earth’s Rotation and Tilt

• The time it takes the Earth to revolve around the Sun is 365 days (one year). Every 23 hours and 56 minutes (one day), the Earth rotates on its axis. The tilt of the Earth’s axis gives us seasons.

• As the Earth rotates, it is tilted at 23.5º from vertical. Depending on what part of the year (orbit around the Sun) and which hemisphere (North or South) you are at, your location will either be tilted toward the Sun (summer) or away (winter).

• At the equator, the Sun’s energy strikes the Earth the same all year long - in other words, there are no seasons!

• It is this tilt that also changes the length of the daylight hours each part of the Earth receives.

• The shortest day (Winter solstice) occurs when we are tilted the most away from the Sun, while the longest day (Summer solstice) occur when the tilt is closest to the Sun.

• The Spring and Autumnal equinoxes occur when the number of hours of light and dark are equal.

See pages 414 - 415


Eclipses

• An eclipse occurs when a celestial object obscures the normal view of another celestial object.

• Eclipses frightened ancient peoples, who believed supernatural forces controlled the Sun and Moon.

• Solar eclipses occur when the Moon comes between the Earth and the Sun. Normal daylight disappears, and only small amounts of light make it to the Earth during the few minutes it takes the Moon to pass between the Earth and Sun.• The Moon is so small, its full shadow only covers a small portion of the

Earth. This area is said to undergo a total eclipse.• Lunar eclipses occur when the Earth comes between the Moon and the Sun.

The Earth’s shadow causes the full moon to slowly disappear, again taking a few minutes before the shadow passes.• Lunar eclipses happen far more frequently than solar eclipses.

See pages 416 - 418


Constellations and Meteors

• Ancient civilizations studied the night sky for patterns, and created many myths based on patterns they recognized from their lives.

• The night sky appears to be flat because of the huge distances between stars, but actually the stars in one constellation can be several thousand, or even millions, of light years apart!

• In the northern hemisphere, the “pointer stars” of Ursa Major show the location of the North Star, Polaris. The location of Polaris is special, as it does not change position throughout the year, unlike all other stars.

• Meteoroids are pieces of space rock floating through space without a specific orbit. When they pass through the Earth’s atmosphere, they begin to heat from friction, and are called shooting stars. If any of the meteoroid reaches the Earth’s surface, it is called a meteorite.




12.2 Aboriginal Knowledge of the Solar System

• Long before modern science, the Aboriginal peoples of the West Coast developed systems based on observations of space and celestial bodies.

• Aboriginal cultures have a holistic world view, where all realms of the physical and spiritual world are connected to form a whole. Western science is based on the physical realm only.

• Observations of the Sun and Moon allowed for the development of hunting, fishing and agricultural cycles.

• By observing the position of celestial objects in the sky, accurate navigation and distance calculations could also be made.

See page 426


Aboriginal Knowledge of the Solar System

• The aboriginal peoples of British Columbia made daily decisions using their knowledge of the moon, planets and stars.

• Fishing was often influenced by lunar positioning.• It was observed that there were 13 lunar months, of 29.5 days,

throughout the year.• The Coast Salish, for example, named these lunar months, and

associated each with knowledge of connected seasons, cultural activities and traditions.

• Navigation was often determined by the positions of the stars and planets in the night sky.• By recognizing the patterns the stars and planets followed,

predictable seasons were followed from year to year.




12.3 Exploring Space: Past, Present and Future

• Until the invention of the telescope, knowledge of space was very weak, and mythology and speculation were the rule.

• The telescope was invented in the 17th century by the Dutch eyeglass maker Lippershey.

• There are two main types of optical (light) telescopes: refracting and reflecting.• Refracting telescopes use lenses to gather and focus

light• Reflecting telescopes use mirrors to collect light and

project it onto an eyepiece.

See pages 432 - 433


Non-Optical Telescopes

• Early optical telescopes improved viewing of space greatly, but other electromagnetic waves could also be used to gather information about space.

See pages 434 - 435

• X-rays, gamma rays and radio waves can all be gathered and analyzed to learn about space.

• Radio telescopes look like satellite dishes.

• By joining radio telescopes together in a network, results can be obtained as though one very large telescope was being used.

From the Commonwealth Scientific and Industrial Research Organization


Space-based Observation

• As good as many of the telescopes on Earth are, by moving outside the atmosphere, space-based observation has become our most powerful method of space observation.

See pages 435 - 438

• Satellites launched from Earth provide us with communication and safety every day.• Geosynchronous satellites orbit at the

same rate as the Earth rotates, and stay above one point.

• Probes launched from Earth have visited Venus, Mars and Saturn’s moon Titan, and have traveled through space to the far reaches of our solar system.

• Rovers are used to maneuver scientific equipment after landing on planets and moons.

The surface of Saturn’s moon Titan.


The Technology of Space Travel

• The challenge of using rockets to launch scientific equipment - and astronauts - into space now sees us attempting to establish colonies in space.

• A rocket is used whenever we want to get something - called a payload - into space.• The rocket has a large amount of thrust, and very little drag, in order

to break through the Earth's atmosphere.• The space shuttle program also uses rockets for launch, but also relies

on having the equipment return to Earth safely for return trips.• The International Space Station is an attempt to provide a location in space

from which to operate without needing to always use rockets to get there.

See pages 439 - 440


Space Travel

• Early attempts at space travel were unmanned, or carried animals. In the past 40 years, we have sent humans into space, as well as having them return safely.

• International collaboration promotes friendly politics.• Canadians have aided in space travel by contributing to the development of the

International Space Station, as well as work on the Canadarm system for the Space Shuttle, as well as sending astronauts on space missions.

• Many technological advancements have occurred due to research done for space travel.

• Soon, average citizens may be able to afford to travel into space for recreational purposes.

• Terraforming is a process where previously uninhabitable locations, such as the Moon or Mars, would be changed to look and function as Earth does.

See pages 441 - 442


The Risks of Space Travel

• Perhaps more than in any other area, space travelers rely heavily on the equipment used for travel to provide safety.

• Two shuttle failures have resulted in the loss of several astronauts.• Our equipment is very sensitive to the debris found in space, from large fuel

tanks to small flecks of paint.• Sometimes, this debris can also re-enter the Earth’s atmosphere and

threaten us on the surface.• Space poses a huge advantages to those who control it, and have access to its

resources.• Environmental, safety and political concerns can arise if we do not use

space ethically.

See pages 443 - 444


New Ideas for Interplanetary Travel

• To reach farther into space, particularly for manned missions, new methods of transportation will be necessary.

• Our current space travel technology uses very large amounts of fuel to travel relatively short distances with very few passengers.

• The ‘space sled’ uses magnetic technology to help propel a small craft without the use of much fuel.

• A ‘space elevator’ would be very useful for moving people and materials into space without the constant use of rockets.

See page 445Take the Section 12.3 Quiz


(c) mcgraw hill ryerson 2007 10.1 the early universe until 100 years ago, scientists believed...

Documents