Topic 1.0: Human Understanding Of Space And Earth Changes Flashcards
Solstices
Occurs in both the summer and the winter
It comes from the Latin words that mean “sun” and “stop”
Prediction of the approach of summer and winter was important to early people’s and many ancient civilizations built huge monuments to honour their beliefs about the change
They had a fairly accurate observations of the position and path of the sun throughout the year
Summer solstice
In the northern hemisphere, the summer solstice occurs near June 21
It marks the longest period of daylight in the year and represents the start of summer
Winter solstice
Occurs near December 21 in the Southern Hemisphere and marks the shortest day of the year and the start of winter
Stone hedge
Is in southern England and is made of multiple stones that are standing in concentric circles. The massive stones mark the summer and winter solstices
Equinox
Occurs twice… One in the spring (about March 21) and one in the fall ( about September 22)
The word comes from the Latin words that mean “equal” and “night”
During an Equinox the day and night are the same length
Mayans of Central America
Built an enormous cylinder shaped tower at Chichen Itza a long time ago to celebrate the occupancy if the two equinoxes
Ancient Egyptians
Built many pyramids and other monuments to align with the seasonal position of certain stars
The entrance passage of Khufu, the great pyramid at Giza, once lined up with Thuban ( a star from the constellation Draco) This helped them find the closest point to north.
Aboriginals of southwestern Alberta
2000 years ago they used large rocks to build medicine circles in which key rocks aligned with the bright stars that rose in the dawn.
Geocentric model
about 2000 years ago, Aristotle proposed a earth centred model to explain planetary motion
The model showed earth as the centre, surrounded by a series of concentric spheres that represented the paths of the sun, moon, and five planets known at the time
He asking believed that the stars were fixed on the outer centric sphere explaining that’s why they didn’t move
Heliocentric model
In 1530, Nicholas Copernicus proposed a dramatically different model, one that explained planetary motion more simply than the geocentric model
He suggested that the sun was at the centre and the earth and other planets revolved in orbits around it.
Galileo Gallilei
Used the new technology of the telescope that was discovered a little less than 100 years later
He confirmed solid evidence of Copernicus’s theory!
He also discovered mountains on the moon, spots on the sun, moons orbiting Jupiter and much more.
Johannesburg Kepler
Is overs that the planets didn’t travel in circular orbits but in ellipses.
He discovered the missing part of Copernicus’s theory and made the solar system understanding more valid than ever before.
Quadrant
Designed by the Egyptian astronomers to measure a stars hight above the horizon
Astrolabe
Used by Arabian astronomers for centuries to make accurate charts of star positions
Cross staff
Invented in the 14th century by Levi Ben gurson to measure the angle between the moon and any given star
Telescope
Invented in the late 16th century
It revolutionized astronomy and allowed astronomers such as Galileo to see the night sky more than ever possible before
They could view the distance between planets and showed the existence of planet neighbours in the solar system
Today, almost 500 years after the early telescope, we started to use satellites that orbited earth and showed us even more about our universe. Such as learning that our star is only an average star and that there are billions of other galaxies out there!
Astronomical units
Used for measuring “local” distances from the centre of earth to the centre of the sun
Astronomers use this when describing positions of the planets relative to the sun.
Light years
It equals the distance that light travels in one year.
Used for vast distances beyond our solar system that are too large for our tiny measures in astronomical units
Light travels at a speed of 300 thousand KM per second
This means that we may be only receiving the light from stars that may no longer exist!
Stars
Hot, glowing balls of gas (mainly hydrogen) that give off a tremendous light energy
The number of stars in the universe is in the billions of billions
Stars can vary greatly in their colours as well as mass, size and density
The colour of star depends on its surface temp… Hot stars look blue and cooler stars look red!
Hertzsprung Russell diagram
Compared the surface temp of a stars with other stars brightness
He plotted the data in a diagram that discovered the distribution of star temp and brightness is not random
The diagram puts the stars into distinct groupings and shows part of our theory today of how stars change over periods of time.
Nebulae
Huge accumulations of gas and dust
It is composed of about 75% hydrogen and 23% helium
The other 2% is oxygen, nitrogen, carbon and silicate dust
Interstellar matter
Can come from exploding stars and it is gases and dust that exist in space between stars.