Astronomy Exam 1
A star is 230 light years away. The light we see tonight from that star left it
230 years ago
Light travels 3 x 105 kilometers every second.
300,000 kilometers
The angular size of your finger at arm's length is about 1°. How many arcseconds is this?
60 x 60 = 3600 arcseconds
A large body in space that consistently makes its own light (instead of merely reflecting another body's light) is called
A Star
What is an epicycle?
A small circle in the planet's motion in the sky
How was careful observation of the sky used in early cultures?
All of the above
What is Out There
Astronomers have found many different kinds of objects beyond Earth. The Sun is an example of a star, which is a giant glowing ball of gas that shines from nuclear reactions. Round objects that revolve around (orbit) a star are called planets. Large collections of billions of stars, like the Milky Way, are called galaxies. Moons are smaller objects that orbit a planet. Astronomers call the sum total of everything that is out there the universe.
Objects are located on the celestial sphere in units of
Degrees
When an astronomer describes the altitude of something in the local sky, he or she means
How high above the horizon something is in the sky, in units of degrees
Circles in the Sky
If you were standing at Earth's north pole, and you looked up to the zenith (the point directly above your head), you would be looking at the point where the _____________ is located. At the Earth's North Pole, the celestial equator would be at your __________. If, on the other hand, you were at the Earth's equator, you would see one point of the celestial equator pass through your ____________. If you are looking at the sky from the continental United States, the north celestial pole would have an angular height (an altitude) equal to your _____________. Right now, the star located very close to our north celestial pole is ___________.
What causes the seasons?
In summer, the Sun is up for more hours and in summer, the Sun climbs higher in the sky so its rays hit the ground more directly
What makes Polaris a special star?
It is near the axis about which the sky turns and its azimuth (direction) is always due north
Why is it generally warmer a month or so after the summer solstice (the "official" start of summer) than it is on the solstice itself?
It takes time for the Earth to warm up and cool down.
Suppose that the Moon was a cube, but everything else was the same-it kept one side facing Earth as it orbited. What would its phases be like?
It would only show "new" and "full" phases
Put these in order of size. Moon, Galaxy, Sun, Jupiter
Moon, Jupiter, Sun, Galaxy
Put these astronomical places in order of increasing distance from us; start with the closest and end up with the most distant. Andromeda Galaxy, Center of the Milky Way Galaxy, Moon, Pluto, Sun.
Moon, Sun, Pluto, Center of the Milky Way Galaxy, Andromeda Galaxy
As seen from North America, stars near Polaris in the sky
Never set
Earth revolves around the center of the Milky Way Galaxy
Once every 230 million years
If you were on the Moon, Earth would
Show phases opposite to the Moon (when it is full Moon it is new Earth, etc)
Of these which is the closest to us? The center of the Milky Way, The closest spiral galaxy, The Sun, Mars, The Moon
The Moon
The natural object (not one that humans built) in space that's closest to Earth is
The Moon
Put the objects in order of distance from closest to furthest away from Earth. Sun, Pleiades Star Cluster, Coma Cluster of Galaxies, Moon, Andromeda Galaxy
The Moon, Sun, Pleiades Star Cluster, Andromeda Galaxy, Coma Cluster of Galaxies
Directly above Earth's north pole, on the celestial sphere, is
The North Star, Polaris
The star that provides energy for life on Earth is
The Sun
These objects in order from nearest to farthest from Earth
The Sun, Pluto, Alpha Centauri, the Milky Way, the Andromeda galaxy
Of these, which is the largest? Jupiter, The Milky Way Galaxy, The Universe, Earth, The Solar System
The Universe
When an astronomer describes the azimuth of something in the local sky, he or she means:
The direction toward something-such as north, south, east, or west
If the tilt of Earth's axis to its orbital plane was 40 degrees, instead of 23 ½, but its distance from the Sun remained the same, what would happen to the seasons?
They would become more extreme-winter colder and summer warmer
If you had a very fast spaceship, you could travel to the celestial sphere in about a month.
This statement doesn't make sense because the celestial sphere is a concept and not a physical object
How often can there be a solar eclipse (at any point on the earth)?
Twice every year at the nodes of the lunar orbit
The North Star (Polaris) is 50° above your horizon, due north. Where are you?
You are at latitude 50°N
What is the Milky Way Galaxy?
a disk-shaped collection of more than 100 billion stars, including the Sun
When we look at the most distant observable objects in the universe, we see them
as they were about 14 billion years ago
A map of the entire sky is called:
celestial sphere
The sky is divided into 88 zones called
constellations
The Astronomical Unit (AU) as defined by astronomers is
the average distance between the Earth and the Sun
Earth's axis of rotation is tilted about 23.5 degrees relative to
the axis of its orbit around the Sun
A light year is
the distance that light travels in one year
Which of the following answers has the objects listed in order from smallest to largest?
the solar system; the Milky Way; the Local Group
Which of the following is the Earth NOT located in?
you can't fool me, we are located in all of these
What is the observable universe?
everything out to a distance of about 14 billion light-years from Earth
By the term universe, astronomers mean
everything that we can observe
If the age of the universe were compressed to one year, with the Big Bang on January 1, about when did the solar system form?
in September
Most of the elements that make up Earth and all life on Earth, including humans, were formed
inside stars that died before Earth formed
Why can't we see galaxies 15 billion light-years away?
looking 15 billion light-years away means looking to a time before the universe existed.
The brightest stars in a constellation...
may actually be quite far away from each other.
The laws of nature (as determined by scientists)
more than one of these
Earth rotates on its axis
once a day
The moon revolves around the earth
once a month
Earth revolves around the sun
once a year
Ever since the Big Bang...
space has continued to expand, with clusters of galaxies moving away from each other, but stars remaining in galaxies and galaxies remaining in clusters.
Light-Years and Light Travel Time
Because cosmic distances are so vast, astronomers use light-years as their unit of distance. One light-year is defined as the distance light travels in a year. The nearest star is a little more than 4 light-years away from us. When we see light from a galaxy 2 million light-years away, it has taken 2 million years to reach us. Light from the Sun takes a little more than 8 minutes to reach us.
When was Earth known to be circular and its circumference measured?
By the greeks
The way scientists know that a hypothesis in astronomy is a reasonable description of nature is to
do experiments and observations about the predictions of the hypothesis
