alignment An alignment of a constructed or natural feature with the celestial movement of the sun, moon, or stars, or with the cardinal directions.
Anasazi Navajo word meaning "ancient ones" or "ancient enemy." For many years this was the name used for the ancestors of people living in the Four Corners region of the Southwest. Today, most people use the term ancient Puebloans or Chacoans.
archeoastronomy A field of scientific research that studies the astronomy of ancient cultures.
butte A hill with sloping sides and a flat top that rises abruptly above the surrounding area.
carbon-12 The ordinary, nonradioactive form of carbon.
carbon-14 A A radioactive isotope of carbon, used for dating archeological and geological samples. Compared to ordinary carbon (carbon-12), carbon-14 has two extra neutrons in its nucleus.
cardinal directions The four directions - north, south, east, and west.
Casa Rinconada Spanish name for a large kiva in Chaco Canyon, meaning "house of corners."
Chacoans/Chacoan People The term for a large group encompassing more than nineteen Native American tribes that once inhabited the Four Corners region. When Spanish explorers came to this region, they named the entire populace Anasazi (or "ancient ones" in the Navajo language).
Chaco Phenomenon A term coined to refer to the distinctive and sometimes perplexing features of the Chacoan culture, which included great houses built in a desolate area at the center of a widely distributed population in the Four Corners region.
coronal mass ejection An ejection of large amounts of matter from the sun's atmosphere, or corona. The corona is contained by magnetic fields that can suddenly rearrange, releasing an enormous bubble of matter.
dendrochronology Tree-ring dating, which uses the distinctive pattern of growth rings in trees to establish the age of a living or dead tree.
equinox Two midpoints in the sun's yearly cycle. In the Northern Hemisphere, the vernal (spring) equinox occurs around March 21, the autumnal (fall) equinox around September 23. These are the days in the year when the hours of daylight and nighttime are equal.
Four Corners Region where New Mexico, Arizona, Utah, and Colorado meet.
gnomon A vertical stick or marker that casts a shadow for the purpose of determining time.
great house Term for the major sites at Chaco Canyon that describes ancient buildings containing many rooms and kivas. The great houses represent a major and sudden architectural change in the building style of the Puebloans.
great kiva An unusually large kiva associated with a Chacoan great house.
Hopi A Puebloan people in northeastern Arizona.
isotope One or more atoms of the same element that have the same number of protons but different numbers of neutrons. For example, carbon-14 is an isotope of ordinary carbon, carbon-12. Carbon-14 has eight neutrons in its nucleus, while carbon-12 has only six.
kiva A room, usually circular and partially below ground, used for ceremonial purposes.
Maya Native people of southern Mexico and Central America.
North Road A thirty-five-mile road that leads directly north from Chaco Canyon to the badlands of Kutz Canyon.
North Star Polaris, the star that roughly marks the northern point of the earthís axis.
pecked basin A small, bowl-shaped depression carved out of rock where Chacoans left offerings, usually corn meal.
petroglyph Art that is carved into rock.
pictograph Art that is painted onto a rock.
Pueblo A term for a Native American town or community that encompasses not only the physical town but the cultural aspects of a tribe. Also used as a term for describing a group of nineteen tribes in the Southwest (Puebloans).
radiometric dating A technique whereby the predictable decay of naturally occurring radioactive elements is used to establish the age of an object. Elements used in radioactive dating include carbon-14, uranium, thorium, rubidium, and others.
rock art General term describing both pictographs and petroglyphs.
sandstone Rock formed from compressed sand.
solstice The day of the year when the sun reaches its extreme northerly or southerly point. In the Northern Hemisphere, the summer solstice happens near June 21, when the sun is at its northern extreme; the winter solstice occurs near December 21, when the sun is at its southern extreme.
supernova An exploding star. The remnants of a supernova in our galaxy in 1054 form what is now the Crab Nebula, found in the constellation Taurus.
totality The phase during an eclipse when the face of the moon or sun is completely blocked.