Astronomy
Wikipedia has a list organized by country for ancient observatory sites. Ancient Astronomical Observations: Find out how ancient people created structures to help them make astronomical observations. (Note that the Aztec Sun Stone is a calendar, not an observatory). Stanford Solar Center has an excellent list here. Find a NASA newsletter on a particular ancient observatory from the left side menu. Get research level data on Chankillo Peru, and the Canary Islands here.
A tour of the universe of scale. From the quantum to the cosmos.
Solar System Basics: review basic motion of the earth to better understand day/night, moon, and seasonal cycles. Understanding the celestial sphere a bit better. Go much deeper here. Play God by downloading your own planetarium software.
Electromagnetic Spectrum basics.
Have a look at the sun in real time in various wavelengths of light.
Spectroscopy helps us understand what stars are made of, their temperature, distance, motion, interactions, etc.
A video to help us understand the Doppler Effect.
What each wavelength of light tells us about the universe.
How redshifted and blueshifted spectra tell us the motion of stars and galaxies.
A new way of measuring the expansion of the universe by analyzing a distant supernova seen in several different places at different times due to gravitational lensing.
The history of the universe from the Big Bang to now and far into the future. Simple version. More detailed version. The absolutely everything version.
Veritasium video on dark matter. Another shorter video on dark matter, and one on dark energy.
Youtuber Science Asylum on evidence for dark matter, and possible explanations.
An excellent video of the history of the universe. Cosmology explained by Arvin Ash.
Star basics. Life cycle of a star. Size comparisons for stars. Focusing on Super-Massive Stars. With great accents. Neutron Stars information. A high-level explanation of white dwarf, neutron star, and black hole formation. An interactive database of the nearest stars to Earth, designed by Google engineers. Could a nearby supernova cause extinction on Earth?
Fantastic explanation of the images of black holes made by the EHT collaboration.
How to find Exoplanets like the solar system found around Trappist-1.
A database of the thousands of exoplanets found so far.
Play with asteroid impacts on Earth.
Astronomy Questions.pdf