Unit E: Section 1.0 Flashcards
What did the First Nations believe about the sky?
the night sky was a pattern on a blanket. The blanket, they believed, was held up by a spinning “world pole,” the bottom of which rested on the chest of a woman underground named Stone Ribs
When does the summer solstice occur in the northern hemisphere?
June 21
What does the summer solstice mark?
The longest period of daylight in the year and represents the start of summer.
When does the winter solstice occur in the northern hemisphere?
Winter 21
What does the winter solstice mark?
The shortest period of daylight in the year and represents the start of winter.
When does the spring equinox take place?
March 21
When did the fall equinox take place?
September 22
What happens on an equinox?
Day and night are equal
What did the ancient Mayans build to signify the equinox?
pyramids and other monuments to align with the seasonal position of certain stars.
Who created the Geocentric model?
Greek philosopher Aristotle
Explain the geocentric model
Earth was at the center. Surrounded by a series of
concentric spheres that represented the paths of the Sun, Moon, and five planets known at the time
How many planets were known at the time of the geocentric model?
5
Why did the stars not move in the geocentric model?
They were attached firmly to the outermost sphere
Who proposed the heliocentric model?
Polish astronomer Nicholas Copernicus
Explain the heliocentric model
The Sun was at the centre and Earth and the other planets revolved in orbits around it
What did scientists figure out about the orbits of planets?
They were ellipses and not circles.
What was stonehenge used to predict?
Solstices
What were sundials used for?
To measure the passage of time
What was a Merkhet used for?
To chart astronomical positions and predict the movement of stars
What was a quadrant used for?
To measure a star’s height above the horizon.
What was an astrolabe used for?
To make accurate charts of star positions
What was a cross staff used for?
To measure the angle between the Moon and any given star
What is the Astronomical Unit used for measuring?
Used for measuring “local” distances, those inside our solar system.
What is one astronomical unit used for measuring?
the average distance from the center of Earth to the center of the Sun, 149 599 000 km
What are distances beyond our solar system measured in?
Light years
What is the distance in a light year?
It equals the distance that light travels in one year.
What is a star?
A star is a hot, glowing ball of gas (mainly hydrogen) that gives off tremendous light energy.
What color are hot stars?
Red
What color are very hot stars?
Blue
What diagram did Ejnar Hertzsprung and Henry Norris
Russell make?
They compared the surface temperature of stars with the stars’ brightness (luminosity)
What are nebulae?
Huge accumulations of gas and dust
What is the lifecycle of a star?
- They start in areas called nebulae
- The gravity between the gas and dust caused it to start collapsing into a smaller, rotating cloud of gas and dust.
- Because it is spinning it causes more of the matter join which heats up the core and glows
- Called a protostar
- When the core reaches 10 000 000°C hydrogen turns to helium
What is a protostar?
A glowing ball of matter
What is the main sequence for sun-like stars?
Nebula Sun-like stars Red Giant White Dwarf Black Dwarf
What is the main sequence for massive stars?
Nebula Massive Stars Red Supergiant Supernova Black hole or neutron star
What is the longest part of a life of a star?
Main sequence, converting hydrogen to helium in their cores.
What happens if the hydrogen in a star is used up?
The stable state star shrinks in size, heating the helium core so that it first starts fusing to carbon, then to other elements. Then it will become a red supergiant
What happens when the temperature of the core is to cool to continue the reaction?
The star continues to shrink becoming a white dwarf and then a black dwarf
What is a black hole?
A highly dense remnant of a star in which gravity is so strong that not even light from the radiation going on inside the remnant can escape
What are constellations?
The groupings of stars we see as patterns in the night sky. There are 88 constellations
What are asterisms?
Unofficially recognized star groupings
What is a galaxy?
A grouping of millions or billions of stars, gas, and dust held together by gravity.
What are the types of galaxies?
Spiral
Elliptical
Irregular
What does a spiral galaxy look like?
A spiral galaxy appears to have long curved arms radiating out from a bright central core
What does an elliptical galaxy look like?
An elliptical galaxy has a shape similar to that of a football or egg and is made up mostly of old stars.
What does an irregular galaxy look like?
Has no notable shape and tends to be smaller than the other two galaxy types.
What type of stars provide light in a spiral galaxy?
Young stars provide most of the light in the arms. Older stars provide most of the light in the central region
What type of stars provide light in an elliptical galaxy?
Made up mostly of old stars.
What is the “protoplanet hypothesis”?
A model for explaining the birth of solar systems.
What are the steps in the “protoplanet hypothesis”?
- A cloud of gas and dust in space begins swirling.
- Most of the material (more than 90%) accumulates in the center, forming the Sun.
- The remaining material accumulates in smaller clumps circling the center. These form the planets.
What is the temperature of the surface of the sun?
5500°C
What is solar wind?
The charged particles that flow out of the sun
How is earth protected from solar wind?
By its magnetic field
What are the 2 groups of the solar system?
The inner planets also called terrestrial, or Earth-like, planets; and the outer, or Jovian
What are the characteristics of the inner planets/Terrestrial?
Tend to be smaller, rockier in composition, and closer to the Sun
What are the characteristics of the outer/jovian planets?
The Jovian planets are large and gaseous and are located great distances from the Sun.
What is the order of the planets from the sun?
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
How is mercury similar to the moon?
No atmosphere and therefore no protection from the bombardment of meteoroids, asteroids, and comets.
What does “period of rotation” mean?
How long is one day
What does “period of orbital rotation” mean?
How long is one year
Which planets are bigger than earth?
Jupiter
Saturn
Uranus
Neptune
Where is the asteroid belt located?
Between Mars and Jupiter
What are asteroids?
small, rocky bodies orbiting the Sun and lying mainly in a narrow belt between Mars and Jupiter
What are comets?
Objects made up of dust and ice that travel through space
When do comets tails glow?
When they get close to the sun
What are meteoroids?
Small pieces of rocks flying through space with no particular path
What is a meteor?
When one gets pulled into the atmosphere by Earth’s gravity, the heat of atmospheric friction causes it to give off light
What are shooting stars?
Meteors
What is a meteorite?
If a meteor lasts long enough to hit Earth’s surface
What is azimuth?
The compass direction of which way to face
What is altitude?
How high to look
What is zenith?
The highest point directly overhead
