Quiz 1: Astronomy & The Night Sky Flashcards
What is an AU?
Astronomical Unit, the distance from earth to the sun
What is a parsec?
A distance away with a parallax angle of 1 arc second. About 3.26 light years.
What is the correct order of size of our Observable Universe?
Earth, Solar System, Solar Neighborhood, Milky Way, Local Group, Super Cluster
What is a Joule?
Joules are work done. Force applied of a distance. W=FD
What is a Watt/Power?
The rate a which work is done.
What is indirect knowledge
Seeing the effect of something
What is direct Knowledge?
Something we set out to gain from observing
What is the scientific method?
It is about disproving things through means that are repeatable and consistent.
What is inductive reasoning?
a method of reasoning in which a body of observations is synthesized to come up with a general principle.
What is Deductive Reasoning?
the process of reasoning from one or more statements to reach a logical conclusion.
What is a hypothesis
The assumption made before doing any experiments
What is a Theory?
a principle set to explain phenomena already supported by data.
What is Falsifiability?
the logical possibility that an assertion, hypothesis, or theory can be shown to be false by an observation or experiment.
What is Magnitude?
a unitless measure of the brightness of an object
What is the Celestial Sphere?
an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer
What is a Constellation?
Certain groupings of stars that are imagined to form shapes of creatures or objects.
What is an Asterism?
In observational astronomy, an asterism is a pattern or group of stars that can be seen in the night sky.
What is a Zodiac Constellation?
Constellations behind the sun during a certain month.
How Many Zodiac Constellations are there?
13
Why do we have seasons on Earth?
Because of the Axil tilt of the planet relative to the orbital plane. Whatever end is pointing toward the sun, that half has summer.
Why do Celestial mapping only work on Earth?
Earth is used as the perspective point
What is the Celestial Equator?
the great circle of the imaginary celestial sphere on the same plane as the equator of Earth.
What are the celestial poles?
are the two imaginary points in the sky where Earth’s axis of rotation, indefinitely extended, intersects the celestial sphere.
What is a Sidereal Day?
the time required for the Earth to rotate once relative to the background of the stars
What is a Solar Day?
the time between two successive transits of the Sun over the same meridian.
Why does the Sun appear to move?
This is because of the axial tilt of the Earth. As we rotate the sun sets and rises. As we orbit the sun, the sun’s position on the horizon changes, and the length of the days change.
What is Axial Tilt?
also known as obliquity, is the angle between an object’s rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbital plane.
What is a solstice?
an event in which a planet’s poles are most extremely inclined toward or away from the star it orbits.
What is an Equinox?
the moment the Earth’s Equator on its axis passes the same plane of the Sun’s equator
What is an Elliptical Orbit?
the revolving of one object around another in an oval-shaped path called an ellipse
What is precession?
the motion of a spinning body (as a top) in which it wobbles so that the axis of rotation sweeps out a cone. (due to gravitational influence)
See Image for Azimuth, Altitude, Zenith, Horizon, Celestial Meridian
Basically coordinates of celestial bodies
What is a Vernal Equinox
two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect.
What is Right Ascension?
the astronomical equivalent of longitude. Right ascension is the angular distance of an object measured eastward from the First Point of Aries, also called the Vernal Equinox
What is Declination?
the angular distance of a body north or south of the celestial equator.
What is Parallax?
the observed displacement of an object caused by the change of the observer’s point of view
What is Triangulation?
The process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline
How do we measure distances in space?
Parallax. (Inversely Proportional, 3x Parallax = 1/3 Distance)
What are the Phases of the moon?
Review chart on w2 slides.
What is a Lunar Eclipse?
occurs when the Moon passes through the Earth’s shadow
What is a solar eclipse?
occurs when the Moon passes through the Earth’s shadow
What are the conditions for an Eclipse?
Eclipses only occur when the tilted lunar orbit aligns just right with the Sun.
What is an Umbra?
that part of a shadow in which all light from a given source is excluded. The shadow from a point source of illumination
What is a Penumbra?
the outer part of a conical shadow, cast by a celestial body, where the light from the Sun is partially blocked
What is the Inner Solar System?
The inner four planets
are Mercury, Venus,
Earth and Mars.
They are called the Terrestrial Planets - they are primarily rocky objects with
small atmospheres.
What is the Outer Solar System?
The four outer planets are
Jupiter, Saturn, Uranus,
and Neptune.
They are called the Jovian Planets,
and are commonly thought of as “gas giants” due to their thick atmosphere.
What is Conjunction?
when the planets are close
to the axis between Earth and the Sun
What is Opposition?
when superior planets are
opposite Earth in line with the Sun
What is Inferior Planet?
orbit is closer to the Sun than Earth’s orbit.
Rarely move far from the Sun; can never be visible in the midnight sky
What is Superior Planet?
orbit is further from Sun than Earth’s orbit
