Astronomy Skills List for 9th Grade
• Locate sky objects by their right ascension and declination on the celestial sphere.
• Identify some bright stars and constellations visible each season.
• Explain why the stars appear to move along arcs in the sky during the night.
• Explain why some of the constellations which appear in the sky each season vary.
• Explain the apparent daily and annual motions of the sun.
• Define the zodiac.
• Describe how the starry sky looks when viewed from different latitudes on Earth.
• Define a sidereal day and a solar day, and explain why they differ.
• Explain how astronomers classify objects according to their apparent brightness (magnitude).
• Explain why the Pole Star and the location of the vernal equinox change over a period of thousands of years.
Light and Telescopes
• Describe the wave nature of light, including how it is produced and travels.
Name the major regions of the electromagnetic spectrum from shortest wavelength to longest.
• State the relationship between wavelength and frequency.
• State the relationship between the color of a star and its temperature.
• List the three windows (wavelength bands) in Earth’s atmosphere in order of their importance to observational astronomy.
• Explain how refracting and reflecting telescopes work.
• Define light-gathering power, resolving power, and magnification for a telescope.
• State the two factors that are most important in telescope performance.
• State the purpose of a spectrograph.
• Explain how radio telescopes work.
• Explain why satellite observatories must operate above Earth’s atmosphere, and list some objects they study.
Stars and their Properties
• Describe the method and limitations of the parallax method to determine the distance to stars.
• Describe three types of spectra: emission, absorption, and continuous spectra.
• Explain why emission and absorption spectra are unique for each element.
• Give a general description of stellar spectra, and explain how they are divided into spectral classes.
• Explain how a star’s chemical composition, surface temperature, and radial velocity are determined from its spectrum.
• List several other kinds of information that are obtained from stellar spectra.
• Explain how a star’s proper motion and space velocity are determined.
• Explain the difference between apparent brightness and absolute luminosity.
• Explain the relationship between apparent magnitude, absolute .magnitude, and distance.
• Describe the H-R diagram, including an explanation of the relationship of a star’s mass to its luminosity and temperature.
• Compare red giants and white dwarfs with our sun, in terms of mass, diameter, and density.
• Define four classes of binary stars.
Evolution of Stars
• Define stellar evolution.
• List the stages in the life cycle of a star like our sun according to the modern theory of stellar evolution.
• Explain the importance of the H-R diagram to theories of stellar evolution.
• Explain the relation between a star’s age and its position on the H-R diagram.
• List the three main steps in the birth of a star.
• Describe the energy balance and pressure balance in main sequence stars.
• Compare and contrast what happens in the advanced stages of evolution for stars of large and small mass: planetary nebulas, white dwarfs, supernovas, pulsars and neutron stars, black holes.
• Identify nebula (birthplace of stars), main sequence star, blue giant, red giant, and pulsating variable stars that can be observed in the sky.
• Describe the origins of the different chemical elements and the importance of supernovas to new generations of stars.
• Describe observational evidence for supernovas, neutron stars, and black holes.
Galaxies
• Define a galaxy and a cluster of galaxies.
• State the shape, size, number of stars, and appearance of the Milky Way Galaxy and give the location of the sun and Earth within it.
• Describe the contents of the interstellar medium.
• Compare and contrast emission and dark nebulas.
• Compare and contrast open (galactic) and globular clusters.
• Explain how radio maps of our Galaxy are constructed.
• Explain the method of using H-R diagrams to determine the ages of star clusters.
• Distinguish between population I and II stars.
• Identify the most distant object visible to the naked eye.
• Compare and contrast properties of the three main types of galaxies in the Hubble classification scheme.
• Describe differences between a normal galaxy and each of the following: exploding galaxies, colliding galaxies, radio galaxies, Seyfert galaxies, and quasars.
Cosmology
• Define cosmology.
• Describe the limitations of cosmology.
• Describe the evidence that the universe is expanding.
• State the Hubble law.
• Explain the meaning of the Hubble constant.
• Describe the past, present, and future of the universe according to each of the three main cosmological models—big bang, oscillating, and steady state theories.
• Describe four methods for choosing among the big bang, oscillating, and steady state theories.
• List observations in support of the evolutionary theories.
The Nature of the Sun
• List some reasons why modern astronomers study the sun.
• Define the solar constant, and explain why it is important to know if it is truly constant with time.
• Define the astronomical unit (AU).
• Describe the sun as a star: formation, properties, motion.
• Describe the structure of the sun: core, zone of convection, photosphere, chromosphere, and corona.
• Describe the sun’s rotation and magnetic field.
• List the basic physical dimensions of the sun.
• Describe some modern tools and techniques for studying the sun.
• Describe the origin, properties, and the cyclic nature of sunspots, and describe how sunspot variations are related to solar activity.
• Describe the location, origin, and nature of solar granules, faculae, plages, prominences, and flares.
• Describe the origin and nature of the solar wind.
• Outline the puzzle of the missing solar neutrinos.
Motion in the Solar System
• List the members of the solar system.
• State the essential difference between a planet and a star.
• Describe evidence supporting the condensation theory of the formation of the solar system.
• Explain the phases of the moon.
• Describe the development of our understanding of the solar system, including the contributions of Ptolemy, Copernicus, Galileo, Tycho Brahe, Kepler, and Newton.
• State and apply the laws governing the motions of bodies under gravity.
• Explain the apparent motions of the planets, including retrograde motion.
• Explain why the moon’s sidereal month and synodic month differ.
• Differentiate between the revolution and rotation of celestial bodies.
• Explain the motions of Earth-orbiting satellites and interplanetary spacecraft.
• Compare and contrast the general properties of the nine large planets.
• Describe the minor planets (asteroids).
The Planets
• Compare and contrast the general properties and surface conditions of Mercury, Venus, Earth, and Mars.
• Explain what is meant by "morning star" and "evening star."
• Compare and contrast the atmosphere of Mercury, Venus, Earth, Mars, and Jupiter.
• Describe conditions on Mars at recent probe landing sites.
• Give two observations that indicate that water might once have been flowing on Mars.
• Compare and contrast the internal structure of Earth and Jupiter.
• Explain the theory of plate tectonics (continental drift) in relation to Earth’s geological activity.
• List and give the current explanation for a famous feature visible in a small telescope for Venus, Mars, Jupiter, and Saturn.
• State some properties that Jupiter and Saturn have in common,and some common properties of Uranus and Neptune.
• Tell what is known about the moons of Mars, Jupiter, Saturn, Uranus, and Neptune and describe plans for future exploration of satellites of the planets.
• Describe known properties of Pluto.
The Moon
• Explain the moon’s appearance and motions in the sky.
• Compare the moon and Earth in diameter, mass, average density, and surface gravity.
• Describe the general surface features of the moon.
• Compare and contrast the moon and Earth in regard to geological activity and erosion of surface features.
• Explain the probable origin of lunar craters and maria.
• Describe surface conditions on the moon at the Apollo landing sites.
• Give the current picture of the moon’s internal structure.
• Give the current theory of the moon’s history.
• List some questions about the moon that remain to be answered.
• Describe the relative positions of Earth, moon, and sun during a solar and a lunar eclipse.
Comets
• Describe the current theory of the origin and composition of comets.
• Explain in terms of the current theory of comet structure the changes in a comet’s appearance as its distance from the sun changes.
• Explain the relationship between comets and meteor showers.
• Distinguish between a meteoroid, meteor, and meteorite.
• Give the composition and probable origin of meteorites.
• Explain why comets and meteorites are of interest to scientists.
Origin of Life
• Describe the molecular basis of Earth-life.
• Describe the evidence that indicates life may have evolved spontaneously from nonliving molecules on Earth.
• Describe a scientific theory of the origin and evolution of intelligent life on Earth.
• Describe the search for life on Mars.
• State the evidence for the existence of solar systems other than our own.
• List the factors involved in estimates of the statistical chances for extraterrestrial intelligent life.
• State the dominant current scientific view of interstellar voyages and UFOs.
• Describe several projects in which scientists have searched or are planning to search for extraterrestrial intelligence.