Astronomy Unit Exam 1
What is the shortest wavelength of light that can be detected by the average human eye?
400 nm
One light-year is a distance of approximately
6,000,000,000,000 miles
In modern astronomy, the constellations are
88 non-overlapping sky regions, covering the whole sky.
What is Heliocentric Cosmology?
A Sun centered universe
What is Geocentric Cosmology?
An Earth centered universe
What is the celestial sphere?
An imaginary sphere of large radius which the ancient's believed the whole heavens were plastered onto it.
Ptolemy's model for the solar system was
Earth-centered, with planetary orbits composed of deferents and epicycles.
Ptolemy's Geocentric model for the solar system to explain the apparent BACKWARD motion of planets against the background stars caused him to create the concepts of __________, and _________ into the theory of circular orbits around the Earth
Epicycles and Deferents
How much of the overall sky is north of the celestial equator?
Exactly one-half
An astronomical unit is larger than a light-year.
False
Galileo used a telescope to observe the phases of Jupiter.
False
Who was the first astronomer to build and use a telescope to observe the night sky?
Galileo
Why is the Earth round?
Gravitational force
Who was Ptolemy?
Greek astronomer, made Geocentrism the world standard through the Middle-Ages.
Who invented the telescope?
Han Lippershey in 1608
Who developed the first reflecting astronomical telescope?
Isaac Newton
The celestial coordinate declination is equivalent to longitude or latitude here on Earth?
Latitude
The charged-coupled device (CCD), now used extensively for astronomical imaging, works on what principle?
Light generates electrical charge on a computer-readable multi-element pixel array of detectors.
Is the planet Uranus visible to the unaided naked-eye from Earth?
No
What are the solstices?
Northern and southern most points of the path of the Sun on the ecliptic, i.e., the winter and summer solstices.
The planet Jupiter travels in an elliptical orbit. Our Sun is at one focus of this ellipse. What is at the other focus?
Nothing
What is gravity?
One of four fundamental forces in the Universe.
____ is the point in Earth's orbit where Earth is closest to the sun.
Perihelion
A telescope whose objective is a lens and contains no mirrors is a(n) ____ telescope.
Refracting
The apparent BACKWARD motion of planets against the background stars during their yearly orbits through the heavens is referred to as
Retrograde Motion.
What do the cycles of the Earth determine?
Seasons
Who formulated the law of gravity?
Sir Isacc Newton
Who discovered the invisible infra-red (or heat) portion of the solar spectrum?
Sir William Herschel
Who was the discoverer of the planet Uranus?
Sir William Herschel, in 1781
The Copernican system for planetary motions is
Sun-centered, with the planets moving in perfect circles around our Sun.
Ptolemy's 13 volume treatise on the astronomical knowledge of the ancient world was titled:
The Almagest
What is "angle measure?"
The method of describing the size of an angle, based on units of degrees.
What is an "arc angle?"
The opening between two lines that meet at a point.
Copernicus solved the mysterious apparent BACKWARD, or retrograde, motion of the planets by understanding what about our solar system?
The planets orbit around the Sun at different rates of speed, rather than the Sun rotates around the Earth.
What is the true nature of white light?
What is the true nature of white light?
Are the constellations seasonal?
Yes, on a summer night many of the constellations you can see are different from those you can see on a winter night. But there are some constellations you can see all year long.
A nanometer (nm) is
a unit of length
The force of gravity from one object extends to infinity never going to zero. When we say that gravitation is universal we mean that
all material objects in the universe exert gravitational forces on one another.
An "arc second" is a measure of
angle
A(n) ____ is 1/60th of an arc minute.
arc second
The ecliptic crosses the celestial equator
at two points, known as equinoxes.
What is the equation first used to determine distance to a star?
d = 1/p
Which of the following types of electromagnetic radiation has the greatest energy?
gamma-rays
In terms of wavelengths, gamma rays
have the shortest wavelengths of the named electromagnetic waves.
According to Newton's first law of motion,
if no force acts on it, a moving object will continue in a straight line at a constant speed.
Kepler's first law states that a planet moves around the Sun
in an elliptical orbit, with the Sun at one focus.
Kepler's first law of planetary motion implies that
planets move in elliptical orbits around the sun.
At the summer solstice in the northern hemisphere, our Sun
reaches its highest angle in the sky for the whole year.
The colors of the rainbow, or of white light passed through a prism, from longest to shortest wavelength are
red, orange, yellow, green, blue, indigo, violet
An apparent westward motion of a planet in the sky compared to the background stars (as viewed from the Earth) when observed on successive nights is referred to as
retrograde motion
Two celestial coordinates, which together describe a star's position precisely in our sky, are
right ascension and declination
In the Greek era, it was almost universally believed that
the Earth was at the center of the Universe.
In pre-Copernican astronomy, it was almost universally believed that
the Earth was at the center of the universe.
Parallax is
the apparent motion of an object due to the motion of the observer.
1 AU or 1 astronomical unit is defined as
the average mean distance between the Earth and Sun.
If we could watch the Sun moving day-by-day against the background stars, it would follow
the ecliptic.
If the distance to the next nearest star is 4.24 light-years, then
the light we see left the star 4.24 years ago
The nightly motion of objects across our sky from horizon to horizon is caused by
the rotation of the Earth on its axis.
When viewed from the Earth, the celestial sphere (the background of stars) moves east to west on a daily basis. This motion is caused by
the rotation of the Earth on its axis.
Telescopes are placed in space to view distant galaxies primarily
to avoid the absorption and distortion of the light or other radiations within the atmosphere of the Earth.
The word "planet" is derived from a Greek word meaning
wanderer.
In Galileo's telescopic discoveries of mountains on the moon and spots on the sun were controversial because they suggested that the sun and moon
were not perfect spheres.
What is the distance between the Earth and the nearest star?
1 AU
The first person to derive a method to successfully calculate the distance to nearby stars (d=1/p ) was German Astrophysicist Friedrich Wilhelm Bessel in the year
1838
The speed of light is
186,000 mi/sec.
