Science 9 Unit E Space Exploration Section 1.0

Science 9 Unit E Space Exploration Section 1.0

Section 1.1 Notes : Early Views About The Cosmos.

SolsticeSolstice is the highest and lowest point the sun reaches in the sky. dates: Summer solstice June 21 longest days of sunlight . Winter solstice December 21 shortest days of sunlight.

EquinoxWhen the day and night are at equal lengths.dates: Spring equinox March 21. Fall equinox September 22

What did Aristotle propose? Aristotle made a geocentric model to explain planetary motion putting Earth in the center with the planets orbiting itGeocentric Model:

He placed Earth on the center while the other planets orbited in a circular path. He assumed stars where attached to the outermost sphere he called "Celestial Sphere" Because they did not move. But his model could not explain other planet observations.

After 2000 years Nicholas Coppernicus made a different model to explain planetary motion much more simply. What did Nicholas Coppernicus propose? Coppernicus made the heliocentric model and suggested the sun should be centered while the 5 planets orbited around it in circular paths.Heliocentric Model:

Less complicated than the geocentric model Was a revolutionary idea because it went against religion Johannes Kepler discovered that the planets where not orbitting in circles, they where orbiting in elipeses. Elipeses are oval formed paths for planetary motion.

Section 1.2 Notes: Discovery Through Technology

The Astronomer's Tools

Tools description: Quadrant: Measures star's height above the horizon ans measures angles. Astrolabe: Makes accurate charts of star positions. Cross-staff: Measures the angle between the moon and any given star Early Telescope: Revealed exciting details about Earth's closest planetary neighbors and showed existence of other neighbors in our solar system. Sundials: Measures the passage of time.

Distance and Time in space.Astronomical Unit: [AU] Is used for measuring "local" distances inside our solar system.One AU = average distance from Earth to the center of the sun (149 599 000 km) Distances in our solar system (AU).

Light Years It equals the distance that light travels in a year The distances beyond our solar system and galaxies are too big for AU so light years are used Light travels 300 000 km/s in a year that adds up to 9.5 trillion km.

Section 1.3 Notes: The Distribution of Matter in Space

What is a star? A star is a massive, luminous ball of plasma. Stars group together to form galaxies, and they dominate the visible universe. The closest star to Earth is the sun.Hertzsprung-Russel Diagram:

The color of a star depends on its surface temperature. Very hot stars look blue. Cooler stars look red In the 1920s, two scientists, Ejnar Hertzsprung and Henry Norris Russell, began comparing the surface temperature of stars with the stars’ brightness (luminosity) Instead, as the “Hertzsprung-Russell diagram” shows , the stars fall into several distinct groupings. Part of this pattern has since been accounted for by the current theory of how stars evolve and change over very long periods of time. When they plotted their data, Hertzsprung and Russell discovered that the distribution of star temperature and brightness is not random.Our sun is part of the main sequence in the Hertzsprung-Russel Diagram.

Birth of a star Stars form in accumulations of gas and dust called nebulae. Nebulae is composed of 75% hydrogen, 23% helium, and 2% oxygen, nitrogen, carbon and silicate dust.. interstellar Matter: gas and dust that exist in space between stars from exploding stars.Protostar: a contracting mass of gas in the first stage of a star's formation. building star structure.

Life and death of a star Nebulas can form into sun-like stars or massive stars according to its mass.Sun like stars: when a certain nebula creates a particular mass for a star that is sun-like.Massive stars: when a certain nebula creates a particular mass for a star that is massive. Red giant.: when sun-like stars contract and expand its outer layers.red supergiant: when massive stars contract and expand its outer layers.white dwarf: Sun-like stars collapses and turn into a white dwarf that are hot but very faint.black dwarf: when a star fades completely until it becomes dark and cold.supernova: When a massive star stops burning and begins to cool and gravity becomes stronger and its core collapse causing the star to explode. neutron star: what is left after a supernova.black hole: A small part of sun-like stars that is dense.. Also the last phase.

Star GroupsConstellations: a group of stars that we see as patterns in the night sky. There are 88 constellations recognized by the International Astronomical Union.Asterisms: Unofficial recognized star groupings.Galaxy: A groupings of millions or billions of stars, gas and dust held by gravity.

Section 1.4 Notes: Our Solar Neighbourhood

Protoplanet Hypothesis.1.A cloud of gas and dust in space begins swirling.2.Most of the material (more than 90%) accumulates in the centre, forming the Sun.3.The remaining material accumulates in smaller clumps circling the centre. These form the planets.Solar Winds: Flares the sun releases in every direction.

3 Types of galaxies: Spiral, regular and eliptical

Terrestrial and Jovian Planets. Terrstrial planets are the inner planets like earth. solid rock closer to the sun Planets:Mercury, Venus, Earth, MarsJovian Planets are the outer planets Large gaseous far from the sun Planets: Jupiter, Saturn, Uranus, Neptune.Planet knowledge:Mercury and Venus are the closest planets to the sun Saturn has the largest ring system.Earth is known as the water planet because it can formed in all states(solid, liquid and gas) Neptune is the farthest from the sun and does not receive much sun energy.

Other objects in space. Astroids: Smalls rocks in a narrow belt between Mars and Jupiter.Comets: Objects made out of dust and ice in space. They have tails when it reaches closer to the sun and heats up the comet material that are released and pushed by solar winds.Meteoroids: small pieces of rocks in space.Meteor: are small rocks pulled into the atmosphere by Earth's gravity, The heat friction gives of light which you see. (it just passes by)Meteorite: when the meteor last long enough to hit Earth's surface.

Section 1.5 Notes: Describing the Position of Objects in Space

Locating the object in space.

Azimuth: Will tell you what direction to point [ N, E, S, W}Altitude: Measure how high the object is. Ranges: 0 at the horizon and 90 straight up (closest point on the horizon at an angle.Zenith: Highest point directly overhead, straight above. Azimuth and altitude are measured in degrees.

Determining the Motion of Objects in Space. Planet comes from the Greek word "Wanderer"Celestial sphere is the name given to the very imaginary "sphere of sky" surrounding earth.Celestial equator is the imaginary line around the celestial sphere above Earth's equator.An ecliptic is the path of the sky along which the sun appears to move.Azimuth and altitude coordinates changes when earth rotates on its axis.

The celestial sphere is the name given to the very large imaginary "sphere of sky"surrounding Earth. (Think of Earth lying within a large hollow ball.) The celestial equator is theimaginary line around that sphere of sky directly above Earth's equator. The ecliptic—the apparent path of the Sun through the sky during the year—crosses the celestial equator at thevernal (spring) and autumnal (fall) equinoxes. The Sun's most northerly position on the eclipticmarks the summer solstice. Its most southerly position marks the winter solstice.