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Space
Space
Perspectives of Earth
Summer solstice (June 21) – the longest period of daylight; the start of summer
Winter solstice (December 21) – the shortest period of daylight; the start of winter
Solstices are reversed in the southern hemisphere
Equinox: day and night are of equal length (March 21 and September 22)
The Celts created Stonehenge to mark winter and summer solstices.
African cultures made large stone pillars into patterns to predict the timing of the solstices
Useful to know when to plant and harvest crops
Stonehenge is angled such that on the equinoxes and the solstices, the sun rising over the horizon appears to be perfectly placed between gaps in the megaliths.
Orbits
Ecliptic: path of the sun through the sky during the year, crosses the celestial equator at the vernal (spring) and autumn (fall) equinoxes.
The Sun’s northerly position on the ecliplipse marks summer solstice. Its most southerly position marks winter solstice.
Inuit: the width of a mitt held at arm’s length to gauge the height of the sun above the horizon. When the sun rose to the height of one mitt width, it meant the seal pups would be born in two lunar cycles.
The sun played a role in mythology of ancient cultures (North American natives, Aztecs, Chinese, Inuit, Greeks, Norse, Japanese).
Ancients used rock structures and buildings to align with stars (2700 BC pyramids built in Egypt, Stonehenge).
Models of Planetary Motion
2000 years ago Aristotle developed the geocentric model (Earth-centered model)
Earth was at the center with concentric spheres encircling it
The distant stars were fixed on the outermost or celestial sphere
Predicted the phases of the moon, but little else
Ptolemy added epicycles, smaller spheres attached to the main spheres. This helped make predictions more accurate.
In 1530 Copernicus developed the Heliocentric model: the sun at the center and planets revolved in orbits around it.
In the 1600s, Galileo used a telescope to provide observations to back up this model
Johannes Kepler: orbits of the planets were elliptical, figured out the shape and scaled the entire solar system from the same observations.
Sir Isaac Newton explained elliptical orbits by proving that there is a gravitational attractive force between all objects that pulls them together in an orbit.
Ancestral Contributions
stars make unchanging patterns in the sky which looked like named objects
use the movement of stars to mark months and seasons, led to the development of the calendar
the Sun, Moon and Planets rise and set at different rates from the stars
7000 years ago, sundials were used to measure the passage of time
Egyptians invented a merkhet to chart astronomical positions and to predict the movement of stars.
Egyptians designed a quadrant to measure a star’s height above the horizon.
Arabian astronomers used an astrolabe to make accurate charts of star position.
Levi ben Gurson invented the cross staff to measure angle between the moon and a star.
Hans Lippershey invented the telescope in the late 16th century.
Galileo Galilei improved the telescope and it revolutionised astronomy. He concluded that the stars are much farther away than the planets.
Kepler described the elliptical shape of the planet’s orbits.
Isaac Newton: law of universal gravitation an explanation for the planets’ elliptical orbits.
The introduction of mathematical approaches (Kepler and Newton) into describing the motion of objects within the universe allowed astronomers to make accurate predictions about the motion of objects in the universe.
Distribution of Matter in Space
Astronomical Units (AU): used for measuring “local” distances, inside our solar system. One AU is equal to the average distance from the center of the earth to the center of the sun (149 599 000 km). Astronomers use this when describing the positions of the planets relative to the sun.
Light-year: equals the distance light travels in one year. Used for measures beyond our solar system.
Star Classification and Life Cycle
Star: a hot glowing ball of gas (mainly hydrogen) that gives off light energy. The number of stars in the universe is in the billions.
Stars vary greatly in characteristics The color of a star depends on its
temperature. A very hot star looks blue. A very cool star looks red.
Hertzsprung and Russell: compared the surface temperature with brightness (luminosity). Star distribution in their diagram is not random – there are several specific groupings.
Nebulae (Prostar): area of space where huge accumulations of gas and dust collect and where stars are formed.
Each nebulae is composed of 75% hydrogen and 23% helium. The other 2% is oxygen, nitrogen, carbon and silicate dust.
Some of this interstellar matter came from exploding stars. Depending on the mass of the star formed from a particular nebula, the star will be sun-like (in terms of mass) or massive.
Both types of stars spend most of their lives in this main sequence converting hydrogen to helium in their cores.
Paths of Star Development
Nebula sun-like stars (main sequence) red giant white dwarf black dwarf
Nebula massive stars (main sequence) red supergiant supernova black hole
Red Giant/Red Supergiant: when a sun-like star increases in size and becomes very bright.
White Dwarf: when a sun-like star collapses: white dwarfs are very hot but very faint.
Black Dwarf: when a white dwarf fades. Supernova: an enormous explosion that
marks the death of a massive star.
Black Hole: a dense remnant of a super nova; an object around which gravity is so intense even light cannot escape.
Neutron Star: If the explosion does not destroy a star, the core is left as a neutron star.
Black Hole
Constellations: groupings of stars we see as patterns in the night sky.
Asterism: distinctive star grouping that is not one of the 88 constellations (e.g. Big Dipper which is part of the Ursa major constellation).
Galaxy: a grouping of billions of stars, gas and dust held together by gravity.
Shapes of Galaxies
Spiral: long curved arms radiating out from a bright central core
Elliptical: football or egg-shaped which is made up of old stars
Irregular: no shape and smaller than the other 2; made up of young and old stars
Bodies Making Up Solar Systems
Protoplanet hypothesis (explains the birth of solar systems):
A cloud of gas and dust in space begins swirling
Most of the material (more than 90%) accumulates in the centre, forming the sun
The remaining material accumulates in smaller clumps circling the centre. These form the planets.
Solar Wind: streams of electrically charged particles discharged by the sun in every direction.
Solar wind is the result of solar flares, explosions that force particles from the sun into space.
Some of these particles spiral down the Earth’s magnetic field and enter the atmosphere to produce the Northern and Southern lights (Aurora Borealis and Aurora Australis).
Sun: the centre of our solar system, 110 times wider than the Earth.
The solar system can be divided into two planetary groups: the Earth like (terrestrial) planets and the outer or Jovian planets.
Terrestrial planets: smaller, rockier, closer to the Sun.
Jovian planets: large and gaseous, located greater distances from the Sun with small densities, rings, and many satellites.
Size of space objects
Milky Way (galaxy) > Solar System > Planets (Jovian > Terrestrial) > Moons
Asteroids: small, rocky or metallic, range in size from a few meters to several hundred kilometers across and are found between the orbits of Mars and Jupiter.
Comets: “dirty snowballs” made up of dust and ice, have bright center and a long faint tail that always points away from the Sun. Ex. Halley’s comet.
Meteoroids: small pieces of rock flying through space with no particular path, are as small as a grain of sand or as large as a car. Meteor: (shooting stars) When a
meteoroid gets pulled into the atmosphere by Earth’s gravity, the heat of atmospheric friction causes it to give off light.
Meteorite: a meteor that hits the Earth’s surface
Eclipses
A solar eclipse occurs when the moon passes between the Sun and Earth casting a shadow on Earth.
A lunar eclipse occurs when Earth passes between the Sun and Moon, casting its shadow over the Moon.
Determining Position and Motion in Space
To locate the position of an object in space two questions must be answered, “How high in the sky is it?” and “In which direction?”
This problem can be solved with two measurements. The first is the compass direction called azimuth, with north as 0. The second is how high in the sky and is called altitude, which ranges from 0 to 90 degrees. Zenith refers to highest point directly overhead.
Spectrometry or Spectrometers
Spectroscopes tell us how fast a celestial body, such as a star, is moving toward or away from us using the Doppler Effect. Light refracted from stars creates a
‘fingerprint’ for each star. Astronomers compare the spectra of a star with known spectra of elements (H, He, Na, Ca) to determine a star’s composition.
The Doppler Effect occurs when sound waves are compressed in front of a vehicle as it speeds along. This results in a shorter wavelength and a higher pitch.
Behind the vehicle sound waves stretch out, creating a longer wavelength and lower pitch.
It can also be used in radar guns to show how fast a vehicle is moving.
The Doppler effect can apply to light-emitting objects such as stars.
When a star is approaching you, its wavelengths of light become compressed. As a result, the dark lines in the star’s spectrum shift toward the shorter-wavelength end of the spectrum – the blue end.
If a star is moving away from you, its spectral lines will be red shifted (moving toward the longer-wavelength part – red end- of the spectrum).
The amount of shift showing up in observations indicates the speed at which the star is approaching or receding.
Another method to determine position and movement of celestial bodies (such as the Sun, Moon and planets) involves using the stars as the frame of reference instead of the Earth.
Note which bright stars are around Venus and take note of the location of Venus relative to these bright stars. The next night, repeat the procedure. Where is Venus in relation to the bright stars? If you continue to take note of the location of Venus in relation to the same bright stars, you will find that it is moving.
Space Exploration
Challenges go fast enough to achieve orbit around
Earth or break free of Earth’s gravity and travel to other planets
keep equipment operating in extreme environment of space
to transport people out and back safely
Environmental Hazards: space is a vacuum, with no air or H2O damaging effects of cosmic rays and
solar radiation risk of being hit by debris or meteoroids no air pressure massive temperature variations
Psychological Challenges long trips in a confined living space
Body and Microgravity microgravity is a condition in which the
gravitational forces that act on mass are extremely reduced
bones expand loss of muscle mass and tone loss of bone mass and density loss of body mass
heart does not have to pump as hard to circulate blood which decreases red blood cell production
muscles become weaker as less walking and lifting occurs: loss of calcium, electrolytes and plasma with excretion of body fluids
Life Support in Space
Space Suit self-contained living system of air, water, a
heating system, a cooling system … a portable toilet
flexible enough to allow fine motor control Oxygen
electrolysis uses electricity to split water molecules into their component elements H2 and O2 -> hydrogen is vented into space
Water water will need to be recycled over and
over because they can only bring a limited supply
technology to filter, purify and recycle the same water (this technology is used on Earth to provide environmentally safe sewage treatment for houses)
Life Support System functions recycle wastewater to produce drinking
water and use recycled water to produce oxygen
remove carbon dioxide from air filter micro-organisms and dust from air keep air pressure, temperature and
humidity stable
Space Transport
To get an object into space, scientists needed to determine at what speed an object could overcome the force of gravity = 28 000 km/h
A rocket is a tube that contains combustible material on one end. The other end is the payload or the device/material that the rocket carries.
Robert Goddard was the first scientist to successfully launch a liquid fuel rocket in 1926.
He discovered that if a rocket had more then one stage, it would fly higher and faster. A stage is a section of a rocket that drops off once the fuel is used up.
In 1942 Werner von Braun developed the first ballistic missile (V-R rocket) during World War II – a bomb powered by a rocket engine. It had the ability to hit a target 200 km away from the launch site.
1957 – Soviet union launched the first artificial satellite called Sputnik
1960’s – Werner von Braun’s team developed the rockets that took the first U.S. astronauts into space
1962 – Canada became the third nation to launch its satellite – Alouette 1
Sputnik (the size of a basketball) and Alouette I
Rocketry relies on a fundamental law of physics: for every action there is an equal and opposite reaction.
An opening in the chamber allows gas to be released producing thrust (push) and causing the rocket to be propelled in the opposite direction.
The speed at which the exhaust leaves the rocket is called exhaust velocity.
There are three basic parts to a rocket: the machinery, the fuel and the payload.
The machinery is everything from the rocket itself to the engines, storage, tanks and fins.
Computers in the air and on the ground work together to control the flight of spacecraft. They calculate orbits, keep track of other satellites (and pieces of space junk), collect, store, and analyze data, and to execute orbital maneuvers of the satellites.
Gravitational Assist
A method of acceleration which enables a spacecraft to gain extra speed by using the gravity of a planet.
The planet’s gravity attracts the craft, causing it to speed up and change direction. The craft “slingshots” away from the planet at a higher or lower speed than it had before its encounter with the planet.
Satellites Artificial Satellites objects built and sent into Earth’s orbit by
humans Natural Satellites small body orbiting a larger body (i.e.,
moon orbiting a planet) Functions of Satellites help us communicate, observe and forecast
weather, predict storms and even find our location on the planet as well as allow for satellite TV, long distance phone calls and GPS for drivers
weather satellites stay in one position above Earth (geosynchronous)
geosynchronous orbit: moves at the same rate as the Earth spins and therefore the same area is observed at all times
result is a 24 hour per day monitoring of weather conditions
observation satellites :take photographs and monitor weather
LANDSAT and RADARSAT follow ships at sea, monitor soil quality, track forest fires, report on environmental change and search for natural resources (not geosynchronous)
REMOTE SENSING imaging devices in a satellite make
observations of Earth’s surface and send this information back to Earth (information can be in the form of photographs or data from energy waves)
provides information on the condition of the environment on Earth, natural resources and effects of urbanization
Global Positioning System (GPS) 24 GPS satellites are in orbit around
Earth, which means there are at least 3 above any given location in the world at any time
radio signals from satellites are picked up by a hand-held receivers
signals are translated by a computer in the receiver, which shows on a digital displace the operator’s position in relation to the satellites
Optical Telescopes
gather and focus light from stars so that we can see it
the larger the area of the lenses or mirrors in a telescope, the greater the ability of the telescope to see distant objects
the objective lense is the larger of the two lenses at the front of the tube
the eyepiece is the lense you look through the image is distorted because of
atmospheric interference
Refracting telescope uses 2 lenses to gather and focus
starlight limited size as any diameter over 1
metre will cause the glass to warp
Reflecting telescope uses mirrors to gather and focus
starlight newer models use segmented mirrors
(segments to form one large mirror) because they have enormous light-gathering ability and resolving power
Combination telescope Interferometry: using telescopes in
combination detect objects in space more clearly
and at greater distances
Hubble Space Telescope
reflecting telescope, orbiting 600 km above Earth, uses a series of mirrors to focus light from extremely distance objects
Earth-based telescopes are limited in their viewing ability by interference from moisture, clouds, air pollution and light pollution.
Adaptive Optics
stars twinkle because the motion of the Earth’s atmosphere refracts light randomly
due to this twinkling or blurring effect, computers have been attached to telescopes in order to sense when the Earth’s atmosphere moves; the computers communicate with devices under the objective mirror so that the mirror is distorted to cancel out this effect
Role of Telescopes
Electromagnetic energy: energy traveling at the speed of
light but having different wavelengths (measurement of distance from one point on a wave to the same point on next wave) and frequencies (equals the number of waves that pass a single point in 1 second) than those of light
Radio telescopes
study radio waves emitted by objects in space millions of times longer than light waves
advantages over optical telescopes not affected by weather and can be
detected day and night not distorted by clouds, pollution or
atmosphere interferometry is used to enhance the
performance, measurement of position, accuracy and detail of the radio images
because radio waves cannot be seen, computers are attached to the radio telescopes to produce color-coded images that correspond to the strength or intensity of the signal (from low intensity to high intensity, the colors are blue, green, yellow, red, white)
Very long baseline interferometry
When 2 or more radio telescopes are connected, without wires, to produce images 100 times as detailed as the largest optical telescopes.
Each telescope’s signal is recorded with timing marks; signals are transferred to computer disks, loaded onto a central computer, and combined to form one image.
Space Probes
unmanned satellites or remote-controlled landers that put equipment on or close to planets too difficult or dangerous to send humans to.
Purposes: sample soil, examine rings and moons, study atmospheric composition, perform geological tests, study how planets form in the solar system and how the characteristics of other planets compare with Earth’s.
Global Positioning Technology
Triangulation based on the geometry of a triangle. Measuring the angle between the baseline and the target object allows you to determine the distance to that object.
Parallax apparent shift in position of a nearby
object when the object is viewed from 2 different places (e.g. passenger versus driver view of the speedometer)
a star’s parallax is used to determine what angles to use when they triangulate the star’s distance from Earth
we use the diameter of Earth’s orbit as a baseline which means measurements are taken 6 months apart
Remote Sensing
the science of taking measurements of Earth (and other planets) from space
applications are: satellite images can be computer processed to
show healthy versus unhealthy vegetation clear-cut and burned forests can be mapped to
show the rates of their degradation water pollution can be imaged erosion can be tracked land use in cities can be observed tracking weather patterns
GPS Satellites
Each GPS satellite transmits data that indicates its location and the current time.
All GPS satellites synchronize operations so that these repeating signals are transmitted at the same instant.
The signals, moving at the speed of light, arrive at a GPS receiver at slightly different times because some satellites are farther away than others.
The distance to the GPS satellites can be determined by estimating the amount of time it takes for their signals to reach the receiver.
When the receiver estimates the distance to at least four GPS satellites, it can calculate its position in three dimensions.
The unit then calculates your location on Earth, using the triangulation method that is programmed into the system. Most units can pinpoint your location to within about 30m.
Today, GPS receivers are used by fishers to mark good fishing spots, by pilots to track their airplane’s position, and by paleontologists to mark dinosaur sites.
Risks and Dangers of Exploration
destructive effects of solar radiation on life and equipment
danger of possible collisions with comets and asteroids
loss of life immense economic loss loss of time spent on work 2003 Challenger destroyed due to
faulty ceramic tiles
1967 Apollo I crew died due to fire on board the spacecraft
1986 Challenger exploded shortly after takeoff
loss of Mars probes (Russian and American) 2001 – only 1/3 of the 2700 satellites are
actually working; the rest are “space junk” early 2001 – Russian space station burned
up on re-entry into Earth’s atmosphere cosmic radiation causes extreme damage
to human cells
Space Junk
Pieces of debris that have fallen off rockets, satellites, space shuttles and space stations and remain floating in space
threat to orbiting space craft satellites, etc as the impact could cause severe damage to their structural integrity
threat to Earth as junk can re-enter Earth’s atmosphere and destroy lives and geographical damage
Canadian Contributions
Magnetic observatory 1839 Sir Edward Sabine established the first
magnetic observatory and discovered the aurora borealis and was related to sunspot activity
Alouette 1 1962 Canada launched Alouette 1, a
satellite for non-military use Anik 1 Satellite 1972 Anik 1 gave the entire country
telecommunications coverage for the first time
Satellite TV 1973 Canada is the first country in the
world to use satellites to broadcast television
Canadarm 1 Canadarm 1, a robotic arm manipulated
by remote control, debuted on space shuttle Columbia in 1981. It launched and retrieved satellites/ fixed optical apparatus on Hubble Space Telescope/ put together modules of International Space Station
Canadarm 2 (also called Canadian Space Station
remote manipulator system SSRMS) 2001 – bigger, stronger and smarter
than its predecessor. Attached to the end of the arm is
the Canada Hand (also called the special purpose dexterous manipulator SPDM)
Issues in Space
Who owns space? property of the first nation to land? eco-tourists who observe or pioneers
who settle and change the planet? owned only by rich nations who can
afford the costs to reach the site?
Who is entitled to use its resources? space resources could satisfy our energy
needs on Earth for a long time minerals from asteroids capturing solar energy and beaming it to
Earth cost of space travel could be cut
substantially by creating space vehicles, supplies, etc directly in space
the Moon can supply hydrogen as fuel for lunar bases and space travel/oxygen for life support/both hydrogen and oxygen used for water supply
Is a space treaty needed? use space exclusively for peaceful
purposes not used as the scene or object of
international discord maybe have nations collaborating
similar to the Antarctica Treaty System
Who is responsible for cleaning up the space environment?
How can we justify spending billions of dollars to send a few people into space when millions of people on Earth do not have clean drinking water?
looking for extra space to house people as the population keeps growing
increase in employment available as other planets are colonized
send robots instead of humans as less danger and cost are involved (lose first-hand experience of humans if we do this)
