Threshold 1
A British astronomer named Fred Hoyle used this term to mockingly describe the idea that the universe began in a single explosive event. Despite being intended as a dismissive insult, the term became widely adopted by the public and scientists alike.
What is "big bang?"
The first generation of stars lit up around 100 million - 400 million years after the big bang, taking the universe across its second threshold and ending this period of cosmic time.
What is the cosmic dark ages?
This is the heaviest element that can be made in the core of a high mass star.
What is iron?
A hypothetical planet named for a Greek Titaness, this Mars-sized body is believed to have collided with early Earth, creating the debris that formed the Moon.
What is Theia?
This phenomenon, related to the Doppler effect, is the stretching of light's wavelength toward the red end of the spectrum, caused by the source moving away from the observer or the expansion of space itself, and it allows astronomers to determine that most galaxies are moving away from us, providing proof that the universe is expanding.
What is red shift?
This was the initial state of the universe, consisting of a "soup" of particles formed by high temperatures and densities, which prevented light from traveling freely through space.
What is plasma?
This is the stage in the life cycle of star where it will spend most of its life.
What is the main sequence?
This is the element that a star uses to sustain itself against the crushing force of gravity for 90% of its life.
What is hydrogen?
This theory describes the movement of the Earth's lithospheric plates and explains phenomena like earthquakes and volcanoes.
What is plate tectonics?
This pillar of big bang cosmology was theorized before being heard through the Holmdel Horn Antenna in New Jersey. Decades later, the Planck Satellite mapped it visually, which provided clues about the Universe's birth, evolution, age, and fundamental properties.
What is cosmic microwave background radiation?
This is how long it took after the big bang for the universe to expand and cool enough for stable atoms to form, allowing photons of light to travel freely through the universe for the first time.
What is 380,000 years?
In this stage of a star's life cycle, it exhausts the hydrogen in its core, expands significantly, and becomes more luminous despite its cooler surface temperature.
What is the red giant stage?
This is the heaviest element a low mass star can make.
What is carbon?
This is the astronomical process in which a celestial body grows in size by attracting and accumulating more matter, typically gas or dust, via gravity as well as random collisions.
What is accretion?
The German meteorologist Alfred Wegener presented compelling evidence for this theory - including the jigsaw-like fit of continental coastlines, the distribution of identical plant and animal fossils on widely separated landmasses, matching patterns of ancient glaciers on different continents, and the presence of similar rock formations and mountain ranges that align when continents are brought together - but he could not explain how it happened.
What is Continental Drift?
This theory, originally devised in the 1980s by Alan Guth, explains why the early universe was so smooth and stable. It proposes that the early universe underwent a period of extremely rapid, exponential expansion shortly after the Big Bang and made the universe incredibly large in a tiny fraction of a second.
What is cosmic inflation theory?
This extremely dense remnant of a low mass star has a high temperature but low luminosity. It is no longer undergoing fusion, so over billions of years, it slowly cools down until it eventually loses all luminosity.
What is a white dwarf?
This cataclysmic event produces all of the heaviest elements in the universe, and due to the immense energy released in the process, it is brighter than the entire galaxy it resides in.
What is a supernova?
Driven by intense heat in Earth's early history, this process causes denser materials to sink to the core and lighter ones to rise, creating a layered interior of a crust, mantle, and core.
What is differentiation?
By using this scientific method to study the oldest rocks on Earth, meteorites, and moon rocks, geologists have determined the Earth is approximately 4.54 billion years old.
What is radiometric dating?
These are the three possible ways the universe will end.
What are the big bounce, big rip, and big freeze?
After a high mass star goes supernova, it will either create a black hole or this kind of star.
What is a neutron star?
Our solar system was formed from this type of a nebula, which is characterized by a very high density of hydrogen and is only possible once heavier elements have been forged by high mass stars and then ejected into space when they die.
What is a molecular cloud?
This semi-fluid layer of the upper mantle, where immense heat and pressure cause molten rock to flow slowly in a convection current, allows tectonic plates to move above it.
What is the asthenosphere?
This term explains the creation of the light elements (hydrogen, helium, and lithium) during the first few minutes after the Big Bang. This process occurred when the universe was extremely hot and dense, allowing protons and neutrons to fuse into stable atoms, which is why there is an abundance of these light elements in the universe.
What is big bang nucleosynthesis?