Science and The Universe Flashcards
(58 cards)
What is our physical place in the universe?
Earth is part of the solar system, which is the Milky Way Galaxy, which
is a member of the Local Group of galaxies in the Local Supercluster.
How did we come to be?
The mater in our bodies came from the Big Bang, which produced hydrogen and helium.
All other elements were constructed from H and He in stars and then recycled into new star systems, including our solar system.
How can we know what the universe was like in the past?
When we look to great distances, we are seeing
events that happened long ago because light travels at a fnite speed.
Can we see the entire universe?
No. The observable porton of the universe is about 14-15 billion
light-years in radius because the universe is about 14-15 billion years old
Light travels at a fnite speed thus … ?
Thus, we see objects as they were in the past: The farther away we
look in distance, the further back we look in time.
Light year
The distance light can travel in one year. About 10 trillion km (6 trillion miles).
How big is Earth compared to our solar system?
The distances between planets are huge compared to their sizes
—on a scale of 1-to-10 billion, Earth is the size of a ball point and the Sun is 15 meters away
How far away are the stars?
On a scale of 1-to-10 the stars are thousands of km away.
How big is the milky way galaxy?
The Milky Way is one of about 100 billion galaxies.
How big is the universe?
10^11 stars/galaxy x 10^11 galaxies = 10^22 stars. It would take more than 3,000 years to
count the stars in the Milky Way Galaxy at a rate of one per second, and they are spread across 100,000 light-years
How many billion light years in radius is the observable universe
14 billion light years
How many galaxies does the observable universe contain?
100 billion
How do our lifetmes compare to the age of the universe?
On a cosmic calendar that compresses the history of the Universe into one year, human civilizaton is just a few seconds old, and a human lifetme is a fracton of a second
Distance of Earth moving in our solar system?
Earth orbits the Sun (revolves) once every year at an average distance of 1 AU ≈ 150 million km. Earth’s axis is tlted by 23.5º (pointng to Polaris).
Does Earth rotate in the same or a different direction then it’s orbit
Earth rotates in the same directon it orbits, counter- clockwise as viewed from above the North Pole.
How is our the stars in our solar system are moving in the Milky Way galaxy?
Stars in the Local Neighborhood move randomly relatve to one another but the stars are so far away that we cannot easily notce their moton
How is our solar system moving in the Milky Way galaxy? (focus on the sun)
Our Sun moves randomly relatve to the other stars in the local Solar neighborhood.
How fast does the sun move
typical relative speeds of more than 70,000 km/hr
How long does it take for the sun to orbit the milky way galaxy
Our Sun orbits the center of the Milky Way in about 230 million years.
How do galaxies move within the universe?
All galaxies beyond the Local Group are moving away from us with expansion of the Universe: the more distant they are, the faster they’re moving
Hubble discovered that:
All galaxies outside our Local Group are moving away from us.
The more distant the galaxy, the faster it is racing away.
What can we conclude from Hubble’s discovery that all the galaxies are moving away from us?
Our galaxy is expanding
How many stars can we see with out naked eye?
We can see over 2,000 stars and the Milky Way with our naked eyes
each positon on the sky belongs to one of (how many) constellatons?
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