Astronomy Exam 1
Cenote
A cenote is a type of sinkhole that contains groundwater. It is typical in the Mexican Yucatán Peninsula and some nearby Caribbean islands. The term comes from a word used by the lowland Yucatec Maya to refer to any location where groundwater can be got at.
gas giants
A gas giant is a large planet composed mostly of gases, such as hydrogen and helium, with a relatively small rocky core. The gas giants of our solar system are Jupiter, Saturn, Uranus and Neptune.
Mesoamerica
A geographic region in the western hemisphere that was home of the Mayan and Aztec civilizations. Mesoamerica is derived from the Greek and means "Middle America." It refers to a geographical and cultural area which extends from central Mexico down through Central America, including the territory which is now made up of the countries of Guatemala, Belize, Honduras, and El Salvador.
pole reversal
A geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged (not to be confused with geographic north and geographic south). ... There have been 183 reversals over the last 83 million years.
Hypothesis
A hypothesis is a proposed explanation for a set of measurements. The mathematical formulation of the hypothesis is called a model. ... Here is an important example of hypothesis-testing from the history of astronomy. The Copernican hypothesis was that the planets travel around the Sun on circular orbits.
lunar eclipse
A lunar eclipse occurs when the Moon moves into the Earth's shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy), with Earth between the other two.
dimension
A measurable extent, such as the three principal dimensions of an object is width, height, and depth. Classical physics theories describe three physical dimensions: from a particular point in space, the basic directions in which we can move are up/down, left/right, and forward/backward. Movement in any other direction can be expressed in terms of just these three.
model
A pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept
planet
A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
planet phase
A planetary phase is a certain portion of a planet's area that reflects sunlight as viewed from a given vantage point, as well as the period of time during which it occurs.
Seasons
A season is a division of the year marked by changes in weather, ecology, and the amount of daylight. On Earth, seasons are the result of Earth's orbit around the Sun and Earth's axial tilt relative to the ecliptic plane. The natural rotation of Earth around the sun forms the basis for the astronomical calendar, in which we define seasons with two solstices and two equinoxes. Earth's tilt and the sun's alignment over the equator determine both the solstices and equinoxes.
rocky planets
A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars.
Unit
A unit is any standard used for making comparisons in measurements
Astronomical Unit (AU)
An Astronomical Unit (AU) is the average distance between Earth and the Sun, which is about 93 million miles or 150 million kilometers. Astronomical units are usually used to measure distances within our Solar System.
Asterism
An asterism is a small grouping of stars that does not make up one of the 88 complete constellations recognized by the International Astronomical Union. The Summer Triangle is an example of an asterism: a group of stars that form a recognizable pattern or shape. The Big Dipper, the Little Dipper and the Great Square of Pegasus are other examples of asterisms.
atom
An atom is a particle of matter that uniquely defines achemical element. An atom consists of a central nucleus that is usually surrounded by one or more electrons. Each electron is negatively charged. The nucleus is positively charged, and contains one or more relatively heavy particles known as protons and neutrons.
electron cloud
An electron cloud is the region of negative charge surrounding an atomic nucleus that is associated with an atomic orbital. It is defined mathematically, describing a region with a high probability of containing electrons.
Electrons
An electron is a negatively charged subatomic particle. It can be either free (not attached to any atom), or bound to the nucleus of an atom. Electrons in atoms exist in spherical shells of various radii, representing energy levels. ... The charge on a single electron is considered as the unit electrical charge.
orbit
An orbit is a regular, repeating path that one object in space takes around another one. An object in an orbit is called a satellite. A satellite can be natural, like Earth or the moon. Many planets have moons that orbit them. Orbit, in astronomy, path of a body revolving around an attracting centre of mass, as a planet around the Sun or a satellite around a planet.
order of magnitude
An order of magnitude is an exponential change of plus-or-minus 1 in the value of a quantity or unit. The term is generally used in conjunction with power-of-10 scientific notation. ... Thus, 2315 is one order of magnitude larger than 231.5, which in turn is is one order of magnitude larger than 23.15.
Archeoastronomy
Archeoastronomy is the study of ancient ways of understanding astronomical phenomena. It inquires in how people of the past ages made sense of celestial events, how they interpreted then and how the sky figured in their daily lives.
astrology
Astrology is the study of the movements of the planets, sun, moon, and stars in the belief that these movements can have an influence on people's lives.
Parallax
Astronomers use an effect called parallax to measure distances to nearby stars. Parallax is the apparent displacement of an object because of a change in the observer's point of view. Astronomers estimate the distance of nearby objects in space by using a method called stellar parallax, or trigonometric parallax. Simply put, they measure a star's apparent movement against the background of more distant stars as Earth revolves around the sun.
apparent magnitude
Astronomers use the term apparent magnitude to describe how bright an object appears in the sky from Earth. The idea of a magnitude scale dates back to Hipparchus (around 150 BC) who invented a scale to describe the the brightness of the stars he could see. -How bright the star appears from Earth
astronomy
Astronomy is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, and comets. Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation).
Astrophysics vs Astronomy
Astronomy is the study of the universe beyond the earth's atmosphere. The main branches are astrometry, celestial mechanics, and astrophysics. Astrophysics is the branch of astronomy concerned with the physical processes associated with the celestial bodies and the intervening regions of space.
astrophysics
Astrophysics is the science of physical processes in the cosmos. It uses data gathered by astronomers using telescopes on Earth and in space - combined with the laws and theories of physics - in order to interpret the universe around us. If astronomy asks what and where, astrophysics asks how and why.
Refraction
Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. ... Astronomical or celestial refraction causes astronomical objects to appear higher above the horizon than they actually are.
Why were cenotes important to the Maya?
Cenotes provided water for drinking and agriculture. However, some, like the Sacred Cenote at Chichén Itzá, were likely ceremonial centers; human sacrifices may have been made there. Chac A Mayan rain god. ... Chacmools may have been used to receive the hearts of people who were sacrificed. Yucatan's cenotes were the main source of fresh water for the ancient Mayans in the Lowlands and had a great significance in their religious beliefs. Not only were cenotes associated with the Maya Underworld due to being underground to some degree or another, they were connected to the goddess Ixchel and the moon.
constellation
Constellation, in astronomy, any of certain groupings of stars that were imagined—at least by those who named them—to form conspicuous configurations of objects or creatures in the sky. Constellations are useful in tracking artificial satellites and in assisting astronomers and navigators to locate certain stars.
Copernican
Copernican system, in astronomy, model of the solar system centred on the Sun, with Earth and other planets moving around it, formulated by Nicolaus Copernicus, and published in 1543. ... It correctly described the Sun as having a central position relative to Earth and other planets. This model positioned the Sun near the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular paths, modified by epicycles, and at uniform speeds.
Declination
Declination, in astronomy, the angular distance of a body north or south of the celestial equator. Declination and right ascension, an east-west coordinate, together define the position of an object in the sky.
eccentricity
Eccentricity is a measure of how an orbit deviates from circular. A perfectly circular orbit has an eccentricity of zero; higher numbers indicate more elliptical orbits. Neptune, Venus, and Earth are the planets in our solar system with the least eccentric orbits. A measure of how much an elliptical orbit is 'squashed'. It is one of the orbital elements that must be specified in order to completely define the shape and orientation of an elliptical orbit.
magnetic pole
Either of the two ends of a magnet at which the field of the magnet is most intense. Each pole is designated by the approximate geographic direction in which it points, either north or south. Like magnetic poles repel; opposite magnetic poles attract. either of two small regions which are located respectively in the polar areas of the northern and southern hemispheres and toward which a compass needle points from any direction throughout adjacent regions also : either of two comparable regions on a celestial body.
Equinox
Equinox, either of the 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.
Fusion
Fusion is the energy process in the Sun. Fusion means "putting together" to form something different. In this case it is hydrogen nuclei, which are simply protons, coming together to form a somewhat more complex helium nucleus. Fusion is the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy.
Geocentric
Geocentric model, any theory of the structure of the solar system (or the universe) in which Earth is assumed to be at the centre of it all. The most highly developed geocentric model was that of Ptolemy of Alexandria (2nd century ce).
Heliocentric
Heliocentric system, heliocentric theory. Heliocentrism, a cosmological model in which the Sun is assumed to lie at or near a central point (e.g., of the solar system or of the universe) while the Earth and other bodies revolve around it. (Sun-centered)
celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with Earth. All objects in the observer's sky can be thought of as projected upon the inside surface of the celestial sphere, as if it were the underside of a dome. Used to describe the position of objects in the sky, the celestial sphere is a fictitious sphere centred on the Earth upon which all celestial bodies can be projected. At any one time, an observer on the Earth's surface can only see half of the celestial sphere since the other half lies below the horizon.
ptolemaic
In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded description of the Universe with Earth at the center. Under the geocentric model, the Sun, Moon, stars, and planets all orbited Earth. Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. ... In order to make his predictions true, he worked out that the planets must move in epicycles, smaller circles, and the Earth itself moved along an equant.
period
In astronomy, the term period usually refers to how long an object takes to complete one cycle of revolution. In particular the orbital period of a star or planet is the time it takes to return to the same place in the orbit.
Cosmological Principle
In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is homogeneous and isotropic when viewed on a large enough scale, since the forces are expected to act uniformly throughout the universe, and should, therefore, produce no observable irregularities in the large-scale structuring over the course of evolution of the matter field that was initially laid down by the Big Bang.
silicate glass
It differs from traditional glasses in containing no other ingredients, which are typically added to glass to lower the melt temperature. Fused silica, therefore, has high working and melting temperatures. Although the terms fused quartz and fused silica are used interchangeably, the optical and thermal properties of fused silica are superior to those of fused quartz and other types of glass due to its purity. For these reasons, it finds use in situations such as semiconductor fabrication and laboratory equipment.
magnetic field
Magnetic fields can be defined in a number of ways, depending on the context. However, in general terms, it is an invisible field that exerts magnetic force on substances which are sensitive to magnetism. Magnets also exert forces and torques on each other through the magnetic fields they create. A planet's magnetic field forms a shield protecting the planet's surface from energetic, charged particles coming from the Sun and other places. The Sun is constantly sending out charged particles, called the solar wind, into the solar system.
magnitude
Magnitude, in astronomy, measure of the brightness of a star or other celestial body. The brighter the object, the lower the number assigned as a magnitude. ... One magnitude is defined as a ratio of brightness of 2.512 times; e.g., a star of magnitude 5.0 is 2.512 times as bright as one of magnitude 6.0.
Near Earth Objects
Near-Earth Objects (NEOs) are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth's neighborhood.
solar eclipse
Occurs when the Moon passes directly between the Sun and Earth and casts a shadow over part of Earth.
mass
On Earth the terms mass and weight are often used interchangeably, but in astronomy and Newtonian physics the mass of an object is related to how much matter it contains. ... Masses are often expressed in the units kilograms (kg), grams (g) or solar masses (M⊙).
Radioactivity
Radioactivity is the spontaneous emission of radiation in the form of particles or high energy photons resulting from a nuclear reaction. ... A substance that contains unstable atomic nuclei is considered to be radioactive. Radioactive decay is a random or stochastic process that occurs at the level of individual atoms.
systematic error
Systematic errors are errors that are not determined by chance but are introduced by an inaccuracy (involving either the observation or measurement process) inherent to the system. Systematic error may also refer to an error with a non-zero mean, the effect of which is not reduced when observations are averaged.
statistical error
Systematic errors primarily influence a measurement's accuracy. Typical causes of systematic error include observational error, imperfect instrument calibration, and environmental interference. For example: Forgetting to tare or zero a balance produces mass measurements that are always "off" by the same amount.
Iridium satellite constellation
The Iridium satellite constellation provides L band voice and data information coverage to satellite phones, pagers and integrated transceivers over the entire Earth surface. Iridium Communications owns and operates the constellation, additionally selling equipment and access to its services.
Kuiper Belt
The Kuiper belt, occasionally called the Edgeworth-Kuiper belt, is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times as wide and 20 to 200 times as massive.
Maya Calendar
The Maya calendar is a system of calendars used in pre-Columbian Mesoamerica and in many modern communities in the Guatemalan highlands, Veracruz, Oaxaca and Chiapas, Mexico. The Maya used what is now known as the calendar round which is made up of 3 interlocking cycles. A cycle of 20 names, a cycle of 13 numbers (which forms the 260-day sacred calendar) and a 365 days solar year. 52 years will pass until the three cycles line up again.
asteroid belt
The asteroid belt is a region of our solar system - between the orbits of Mars and Jupiter - in which many small bodies orbit our sun. The asteroid belt is a region of space between the orbits of Mars and Jupiter where most of the asteroids in our Solar System are found orbiting the Sun. The asteroid belt probably contains millions of asteroids. ... The largest asteroid is called Ceres. It is about one-quarter the size of our moon. It is a dwarf planet.
Supernova
The brilliant point of light is the explosion of a star that has reached the end of its life, otherwise known as a supernova. Supernovae can briefly outshine entire galaxies and radiate more energy than our sun will in its entire lifetime. They're also the primary source of heavy elements in the universe.
Latitude
The definition of latitude is the measurement of a part of the Earth in relation to the north or south of the Earth's equator or the amount of freedom someone is given to deviate from a normal thought pattern or behavior. An example of latitude is a measurement of distance from the equator.
Longitude
The definition of longitude is the distance on the Earth's surface between a specific point and the prime meridian in Greenwich England, measured as a degree or the difference in time from the prime meridian. angular distance east or west on the earth's surface, measured by the angle contained between the meridian of a particular place and some prime meridian, as that of Greenwich, England, and expressed either in degrees or by some corresponding difference in time. Astronomy. celestial longitude.
Ecliptic
The ecliptic is an imaginary line on the sky that marks the annual path of the sun. It is the projection of Earth's orbit onto the celestial sphere. ... The ecliptic is even the starting point for the celestial coordinate system used by astronomers to pinpoint the location of every star, nebula, and galaxy.
kinetic energy
The kinetic energy (KE) of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.
lunar phase
The lunar phase or Moon phase is the shape of the directly sunlit portion of the Moon as viewed from Earth. The lunar phases gradually change over the period of a synodic month (about 29.53 days), as the orbital positions of the Moon around Earth and of Earth around the Sun shift.
focus
The point beneath Earth's surface where rock breaks under stress and causes an earthquake. One of two special points within an ellipse that lie along the major axis; these are the points around which we could stretch a pencil and string to draw an ellipse. When one object orbits a second object, the second object lies at one focus of the orbit. Semimajor axis.
Protons
The proton is a subatomic particle with the symbol p or p+ and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.
Speed
The rate at which an object moves. Its units are distance dividing by time, such as m/s or km/hr. Velocity. The combination of speed and direction of motion; it can be stated as a speed in a particular direction, such as 100 km/hr due north.
tropic (23.5 degrees)
The reason for the location of the Tropic of Cancer and the Tropic of Capricorn at roughly 23.5 degrees north and south, respectively, is due to the axial tilt of the Earth. The Earth is tilted 23.5 degrees from the plane of the Earth's revolution around the sun each year. ... Areas in the tropics can be cold, however.
Synodic v. Sidereal
The sidereal month is the time the Moon takes to complete one full revolution around the Earth with respect to the background stars. ... Thus, the synodic month, or lunar month, is longer than the sidereal month. A sidereal month lasts 27.322 days, while a synodic month lasts 29.531 days. Sidereal and synodic are related to the period of bodies in orbit. "Sidereal" can be defined as the time required for one period to repeat in relation to stars. On the contrary, "synodic" can be defined as the time required for one period to repeat in relation to a solar body.
Solstice
The solstice (combining the Latin words sol for "Sun" and sistere for "To Stand Still") is the point where the Sun appears to reach either its highest or lowest point in the sky for the year and thus ancient astronomers came to know the day as one where the Sun appeared to stand still. A solstice happens when the sun's zenith is at its furthest point from the equator. On the June solstice, it reaches its northernmost point and the Earth's North Pole tilts directly towards the sun, at about 23.4 degrees.
Rotation
The strict definition of rotation is "the circular movement of an object about a point in space." This is used in geometry as well as astronomy and physics. ... All the other points in the ball rotate around the point. Draw a line through the center of the ball where the point lies, and that's its axis.
Theory
Theoretical astronomy at its simplest is the definition of terms to be applied to astronomical effort and the phenomenological results. In essence it is the theory of the science of physical and logical laws with respect to any natural body in the sky especially at night. A scientific theory must make testable or refutable predictions of what should happen or be seen under a given set of new, independent, observing or analysis circumstances from the particular problem or observation the theory was originally designed to explain.
Velocity
Velocity, in physics, is a vector quantity (it has both magnitude and direction), and is the time rate of change of position (of an object). ... In astronomy, it is often quite straight-forward to measure the component of velocity of a distant object along the line of sight to it, by measuring its redshift.
Reflection
When light encounters a discontinuity in the medium through which it is being transmitted, a fraction will be reflected. We define the angle of incidence and the angle of reflection relative to the normal with respect to the plane of discontinuity. Reflection is when light bounces off an object. If the surface is smooth and shiny, like glass, water or polished metal, the light will reflect at the same angle as it hit the surface. This is called specular reflection.
zenith
Zenith is the imaginary point that is directly above a particular location on the celestial sphere. ... The opposite of zenith, that is the direction of the gravitational pull, is called the Nadir, at 180 degrees. Zenith, in astronomy terms, is the point in the sky directly overhead.
zodiac
Zodiac, in astronomy and astrology, a belt around the heavens extending 9° on either side of the ecliptic, the plane of the earth's orbit and of the sun's apparent annual path. The orbits of the moon and of the principal planets also lie entirely within the zodiac. The zodiac, the 12 signs listed in a horoscope, is closely tied to how the Earth moves through the heavens. The signs are derived from the constellations that mark out the path on which the sun appears to travel over the course of a year.
Tychonic System
a model for planetary motion devised by Tycho Brahe in which the earth is stationary and at the center of the planetary system, the sun and moon revolve around the earth, and the other planets revolve around the sun.
absolute magnitude
how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs.
Chicxulub
large crater in Yucatan, some believe it impacted the site that resulted in the demise of the dinosaurs. It is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located offshore near the town of Chicxulub, after which the crater is named.
epicycle
n the Hipparchian, Ptolemaic, and Copernican systems of astronomy, the epicycle (from Ancient Greek: ἐπίκυκλος, literally upon the circle, meaning circle moving on another circle) was a geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. It is a a small circle, around which a planet was thought to revolve, whose centre describes a larger circle (the deferent) centred on the earth.
rotational pole
pole of rotation (Euler pole) A point on the Earth's surface which defines a line through the centre of the Earth about which the relative motion of two plates may be described. The celestial poles are the two points where the projection of the Earth's rotation axis intersects with the celestial sphere.
Nucleus
the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail.
Iridium (Ir)
the chemical element of atomic number 77, a hard, dense silvery-white metal. It has a very high density and melting point. Iridium is the most corrosion-resistant material known. It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings. It was used in making the standard metre bar, which is an alloy of 90% platinum and 10% iridium.
Revolution
the movement of an orbiting celestial object, as a star or planet, completely around another object. apparent movement of the sun and stars around the earth. the time taken for a body to go around an orbit and return to its original position.
K-T boundary
the transition between the Cretaceous and Tertiary periods of geologic time characterized by a mass extinction of many forms of life including the dinosaurs also : a geologic stratum marking this boundary.