Our Cosmic Beginning
This galaxy is home to our Sun and solar system.
What is the Milky Way?
The universe’s history can be traced back approximately this many billion years.
What is 13.8 billion years?
These living animals belong to the dinosaur family and survived the extinction of non-bird dinosaurs.
What are birds?
Earth’s rotation carries a location into and out of sunlight, producing this repeating cycle.
What are day and night?
This is the point in the sky directly overhead.
What is the zenith?
The universe began in a hot, dense state and space expanded in the history described by this model.
What is the Big Bang model?
Earth formed approximately this many billion years ago.
What is 4.54 billion years ago?
A preserved bone, footprint, egg, or other evidence of ancient life is called this.
What is a fossil?
Earth spins around this imaginary line through its geographic poles.
What is Earth’s axis?
This star lies close to the north celestial pole and marks approximately north.
What is Polaris (the North Star)?
This force pulled clouds of matter together to help form stars and galaxies.
What is gravity?
According to the giant-impact model, debris from a collision with young Earth gathered into this natural satellite.
What is the Moon?
This supercontinent began breaking apart during the long history of dinosaurs.
What is Pangaea?
The Sun appears to travel westward because our observing platform, Earth, rotates in this opposite direction.
What is eastward?
As the Sun climbs higher above the horizon, a vertical stick’s shadow generally changes in this way.
What is getting shorter?
Earlier generations of these objects made and scattered many of the heavier elements needed to build rocky Earth.
What are stars?
These three periods, in order, form the main chapters of dinosaur history.
What are the Triassic, Jurassic, and Cretaceous?
This buried crater near Mexico’s Yucatán Peninsula records the impact linked to the extinction 66 million years ago.
What is Chicxulub?
This freely swinging device reveals Earth’s rotation as its swing direction changes relative to the floor.
What is a Foucault pendulum?
This moment occurs when the Sun crosses your local meridian and reaches its greatest altitude for that day; it need not be 12:00 on a clock.
What is local solar noon?
Penzias and Wilson detected this faint ancient glow arriving from every direction, evidence of a hot early universe.
What is the cosmic microwave background (CMB)?
The impact and extinction that ended the Cretaceous occurred approximately this many million years ago.
What is 66 million years ago?
After the impact blocked sunlight, plants and plankton suffered, causing these feeding relationships to collapse.
What are food webs?
When pendulums, sky observations, and other independent tests support the same explanation, scientists call this type of support this.
What is converging evidence?
A tripod camera records star trails because it shares this motion of Earth throughout the exposure.
What is rotation?