https://www.khanacademy.org/science/strengthened-shs-earth-and-space-science-1/x006d5d274c051fd7:origin-and-structure-of-the-earth/x006d5d274c051fd7:what-the-universe-is-made-of/v/our-expanding-universe 2025-11-18T19:31:12.037809628Z Our Expanding Universe In 1998, two independent teams of astrophysicists discovered a baffling phenomenon: the Universe is expanding at an ever-faster rate. The current understanding of gravity can't explain this cosmic acceleration. Scientists think that either a mysterious force called dark energy is to blame—or a reworking of gravitational theory is in order. Travel to the University of California's Lick Observatory to learn how astrophysicists use distant stellar explosions to observe the expansion of space. Then watch a team at Fermilab assemble the Dark Energy Camera, a new device researchers hope will find compelling evidence of what's propelling the Universe to expand at an increasing pace. American Museum of Natural History video https://cdn.kastatic.org/googleusercontent/iV0wC6BxBcsKyZnDep5CHy86s6vf-livntZrc3DS3fN7HFZ90UPBPD4nCc6JEpw0MmdD_nuViL1xm7hlY22QNZdC Our Expanding Universe In 1998, two independent teams of astrophysicists discovered a baffling phenomenon: the Universe is expanding at an ever-faster rate. The current understanding of gravity can't explain this cosmic acceleration. Scientists think that either a mysterious force called dark energy is to blame—or a reworking of gravitational theory is in order. Travel to the University of California's Lick Observatory to learn how astrophysicists use distant stellar explosions to observe the expansion of space. Then watch a team at Fermilab assemble the Dark Energy Camera, a new device researchers hope will find compelling evidence of what's propelling the Universe to expand at an increasing pace. https://cdn.kastatic.org/ka-youtube-converted/LsPqeS5I_QM.mp4/LsPqeS5I_QM.mp4 504 What the universe is made of https://www.khanacademy.org/humanities/oer-project-big-history/xc3079f0f2dd307e4:unit-2/xc3079f0f2dd307e4:big-bang-to-earth-2-1/a/article-the-thresholds-history-of-the-universe 2025-08-13T00:49:52.439041008Z The Thresholds: History of the Universe How did we go from a Universe with a few simple elements to one that includes planets and gold? A lot of it has to do with stars. article https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:earth-in-space/x87d03b443efbea0a:the-solar-system/v/the-solar-system-ms 2024-01-04T21:44:22.995765104Z The solar system Our solar system, formed from a nebula, consists of the sun, eight planets, asteroids, and comets. The inner planets, Mercury, Venus, Earth, and Mars, are rocky, while the outer planets, Jupiter, Saturn, Uranus, and Neptune, are gas giants. The asteroid belt separates these two groups, and the Oort cloud, filled with comets, lies beyond Neptune. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/b8fab4c8-cc6b-4c1c-808c-ae49dbbe513d_1280_720_base.png The solar system Our solar system, formed from a nebula, consists of the sun, eight planets, asteroids, and comets. The inner planets, Mercury, Venus, Earth, and Mars, are rocky, while the outer planets, Jupiter, Saturn, Uranus, and Neptune, are gas giants. The asteroid belt separates these two groups, and the Oort cloud, filled with comets, lies beyond Neptune. https://cdn.kastatic.org/ka-youtube-converted/wTyqO-tfs7Q.mp4/wTyqO-tfs7Q.mp4 296 What the universe is made of https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:earth-in-space/x87d03b443efbea0a:the-solar-system/a/the-solar-system 2022-07-28T07:11:01.209511384Z The solar system Review your understanding of the solar system in this free article aligned to NGSS standards. article https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:earth-in-space/x87d03b443efbea0a:the-solar-system/e/understand-the-solar-system 2025-06-18T15:00:50.065121331Z Understand: the solar system Check your understanding of the solar system in this set of free practice questions aligned to NGSS standards. Lauren Rosebrugh exercise https://www.khanacademy.org/science/revision-up-science-class-6-full-term/x00110b31861f2508:week-4/x00110b31861f2508:beyond-earth/v/the-moon 2025-07-29T05:19:20.326225883Z The Moon Explore the mysteries of the Moon in this fun and fact-packed video. Bitasta Datta video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw The Moon Explore the mysteries of the Moon in this fun and fact-packed video. https://cdn.kastatic.org/ka-youtube-converted/PEplWMXI1YQ.mp4/PEplWMXI1YQ.mp4 304 What the universe is made of https://www.khanacademy.org/science/strengthened-shs-earth-and-space-science-1/x006d5d274c051fd7:origin-and-structure-of-the-earth/x006d5d274c051fd7:what-the-universe-is-made-of/e/moon 2026-04-07T22:59:30.107127435Z Moon This exercise helps you learn about the Moon’s size, surface features, movements, and how humans explore it. Bitasta Datta exercise https://www.khanacademy.org/science/strengthened-shs-earth-and-space-science-1/x006d5d274c051fd7:origin-and-structure-of-the-earth/x006d5d274c051fd7:what-the-universe-is-made-of/v/comets-and-meteors-ur 2025-08-07T23:35:51.501752344Z Comets and Meteors Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Comets and Meteors Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/TwwBQi8ER9M.mp4/TwwBQi8ER9M.mp4 424 What the universe is made of https://www.khanacademy.org/science/revision-up-science-class-6-full-term/x00110b31861f2508:week-4/x00110b31861f2508:beyond-earth/e/comets-and-meteors 2026-04-08T00:54:09.631945657Z Comets and Meteors Let's do some questions! vibhor exercise