Cosmic Distance & Scales
The average distance from Earth to the Sun, which is about 149.6 million kilometers (93 million miles).
What is an Astronomical Unit (AU)?
The perceived change in wavelength emitted from a source moving toward or away from an observer.
What is the Doppler Effect?
The study of how light interacts with matter.
What is Spectroscopy?
The type of galaxy that appears as flat, blue-white disks with central bulges and actively forms new stars.
What is a Spiral Galaxy?
The process in a star's core where hydrogen nuclei combine under high heat and pressure to form helium.
What is Nuclear Fusion?
The unit defined as the distance light travels in one year, equal to roughly 9.5 trillion kilometers.
What is a light-year?
The stretch of light waves toward longer wavelengths, proving that galaxies are moving away from Earth.
What is Redshift?
The type of spectrum that looks like a smooth rainbow without any separate bright or dark lines, produced by hot, dense objects.
What is a Continuous Spectrum?
The spiral galaxy we live in, which measures 100,000 light-years wide and contains over 400 billion stars.
What is the Milky Way Galaxy?
The letter system used by scientists to order stars by surface temperature from hottest to coolest.
What is the OBAFGKM code?
The exact speed at which light travels through space in meters per second.
What is 299,792,458 meters/second?
The compression of light waves toward shorter wavelengths, indicating an object is moving toward Earth.
What is Blueshift?
A spectrum showing dark lines on a continuous rainbow, produced when light passes through a cooler gas.
What is an Absorption Spectrum?
The name of the supermassive black hole located at the center of the Milky Way galaxy.
What is Sagittarius A?
Darker, cooler areas on the Sun's surface caused by intense, localized magnetic activity.
What are Sunspots?
Located 4.3 light-years away, this is the next closest star to Earth after our Sun.
What is Proxima Centauri?
The event 13.77 billion years ago where a dense, hot supermassive ball violently expanded, creating the universe.
What is the Big Bang Theory?
A spectrum featuring bright lines on a dark background, produced by hot, low-density gas.
What is an Emission Spectrum?
Invisible matter that acts like gravitational glue, making up about 26% of the universe and holding galaxies together.
What is Dark Matter?
Light displays in Earth's upper magnetic atmosphere created when solar wind from flares reaches Earth.
What are Auroras?
In the classroom toilet paper activity, this number of toilet paper sheets represented the distance from Earth to Neptune.
What is 30 sheets?
The outdated universe theory which claimed the universe has always been and will always be the same without a beginning or end.
What is the Steady State Theory?
The four distinct properties of distant objects that spectroscopy can reveal to astronomers.
What are composition, temperature, motion, and density?
The American astronomer whose observations in the 1960s and 1970s of galactic rotation speeds provided the first robust evidence for dark matter.
Who is Vera Rubin?
The name of the diagram used to classify stars by graphing their luminosity against their surface temperature.
What is the Hertzsprung-Russell (H-R) Diagram?