Across
- 2. the lightest and most abundant chemical element (atomic number 1), existing as a colorless, odorless, flammable gas
- 4. the scientific study of celestial bodies—such as stars, planets, comets, and galaxies—and phenomena outside Earth's atmosphere, including their motion, chemistry, physics, and evolution
- 5. a pioneering American astronomer who revolutionized cosmology by proving that galaxies exist outside the Milky Way and that the universe is expanding
- 10. renowned American avant-garde stage director, playwright, and designer
- 13. It was released during the "recombination" epoch, when the universe cooled enough (around 3000 K) for electrons and protons to form neutral hydrogen atoms, allowing photons to travel freely through space for the first time
- 16. a massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter
- 17. a colorless, odorless, tasteless, non-toxic, and chemically inert noble gas
- 18. German-born theoretical physicist recognized as the most influential scientist of the 20th century
Down
- 1. German-born American physicist and radio astronomer
- 3. prominent British astrophysicist and cosmologist
- 6. the entire range of all types of electromagnetic radiation, organized by frequency, wavelength, and photon energy
- 7. the totality of all space, time, matter, and energy, encompassing everything that exists, from subatomic particles to galactic filaments
- 8. The visible light spectrum is the narrow portion of the electromagnetic spectrum—roughly 380 to 750 nanometers
- 9. the prevailing cosmological model explaining that the universe began approximately 13.8 billion years ago from an extremely hot, dense singularity
- 11. an instrument that separates incoming radiation (such as light or sound) into its component wavelengths (a spectrum) and records this data onto a detector
- 12. the capacity to do work or produce change
- 14. the displacement of electromagnetic radiation (such as light) towards longer, redder wavelengths as a celestial object moves away from the observer
- 15. the decrease in wavelength (and increase in frequency) of light emitted by a celestial object—such as a star or galaxy—moving toward an observer