https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:space-science/x0e04e0cb682fb793:the-earth/v/earths-place-in-the-universe 2024-01-04T21:44:22.995765104Z Earth's place in the universe Humans have used models to understand Earth's place in the universe. The geocentric model, placing Earth at the center, was replaced by the heliocentric model, with the sun at the center. This change better explains the movement of celestial bodies and shows that Earth's rotation causes the sun's apparent motion. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/367f5f88-2954-4708-a8a2-1ea2aa569771_1280_720_base.png Earth's place in the universe Humans have used models to understand Earth's place in the universe. The geocentric model, placing Earth at the center, was replaced by the heliocentric model, with the sun at the center. This change better explains the movement of celestial bodies and shows that Earth's rotation causes the sun's apparent motion. https://cdn.kastatic.org/ka-youtube-converted/Pv0Re0YEEq0.mp4/Pv0Re0YEEq0.mp4 294 Earth's motions https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:earth-systems-and-resources/x0b0e430a38ebd23f:earths-seasons/v/seasons-ms 2025-08-08T21:39:42.49220884Z Seasons Earth's seasons are not dictated by its distance from the Sun, but rather by its axial tilt. The angle of the Sun's rays determines the intensity of solar radiation, with the equator receiving the highest intensity. This tilt also causes variations in daylight hours, contributing to the change of seasons. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/e5e05c6f-6bcf-4242-8b4b-8e2c8a86de9d_1280_720_base.png Seasons Earth's seasons are not dictated by its distance from the Sun, but rather by its axial tilt. The angle of the Sun's rays determines the intensity of solar radiation, with the equator receiving the highest intensity. This tilt also causes variations in daylight hours, contributing to the change of seasons. https://cdn.kastatic.org/ka-youtube-converted/0r9Lc7oYq5M.mp4/0r9Lc7oYq5M.mp4 306 Earth's motions https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:earth-systems-and-resources/x0b0e430a38ebd23f:earths-seasons/e/earths-seasons 2025-08-08T21:39:42.49220884Z Earth's seasons Apply your understanding of Earth's seasons in this set of free practice questions aligned to AP standards. exercise https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:earth-systems-and-resources/x0b0e430a38ebd23f:earths-seasons/a/solar-radiation-and-earths-seasons 2026-06-25T14:10:39.916233732Z Key points: Solar radiation and Earth's seasons Review your understanding of solar radiation and Earth's seasons in this free article aligned to AP standards. article https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:the-earth-sun-moon-system/x87d03b443efbea0a:seasons/a/seasons 2026-04-26T16:30:39.382257956Z Key points: Seasons Review your understanding of seasons in this free article aligned to NGSS standards. article https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:space-science/x0e04e0cb682fb793:the-earth/e/understand-seasons 2026-04-26T16:30:39.382257956Z Understand: Seasons Check your understanding of seasons in this set of free practice questions aligned to NGSS standards. Khan Academy exercise https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:the-earth-sun-moon-system/x87d03b443efbea0a:solar-eclipses/v/solar-eclipses 2022-10-18T23:43:41.917641962Z Solar eclipses A solar eclipse occurs when the moon casts a shadow on part of Earth. For those inside the shadow, the sun's disk is fully blocked from view. Solar eclipses can occur only during a new moon, when the moon and the sun are on the same side of Earth. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/4c74c630-bd3c-43e4-96a5-25e3325fe286_1280_720_base.png Solar eclipses A solar eclipse occurs when the moon casts a shadow on part of Earth. For those inside the shadow, the sun's disk is fully blocked from view. Solar eclipses can occur only during a new moon, when the moon and the sun are on the same side of Earth. https://cdn.kastatic.org/ka-youtube-converted/cVh7sTN-uNc.mp4/cVh7sTN-uNc.mp4 200 Earth's motions https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:the-earth-sun-moon-system/x87d03b443efbea0a:solar-eclipses/e/understand-solar-eclipses 2026-04-30T05:50:52.043044628Z Understand: Solar eclipses Check your understanding of solar eclipses in this set of free practice questions aligned to NGSS standards. Lauren Rosebrugh exercise https://www.khanacademy.org/science/middle-school-earth-and-space-science/x87d03b443efbea0a:the-earth-sun-moon-system/x87d03b443efbea0a:solar-eclipses/a/solar-eclipses 2026-05-04T10:50:51.323067902Z Key points: Solar eclipses Review your understanding of solar eclipses in this free article aligned to NGSS standards. article https://www.khanacademy.org/science/6th-grade-science-matatag/x1c42f0f13f909d5b:4th-quarter/x1c42f0f13f909d5b:earth-s-revolution-and-rotation/v/lunareclipse 2020-06-23T07:22:41Z Lunar eclipse When the moon passes through the Earth's shadow, it causes the moon to look very unusual for a short period of time. This event is called a lunar eclipse, and it occurs roughly twice a year. NASA video https://cdn.kastatic.org/googleusercontent/tF9Ptc4X_amN96ieGhffAHknVAeD98yuoU_5Ior_6IMVFNtT-yRM2sKvAV701dYSK12KBt8xTaC86-Miud8itJeR9w Lunar eclipse When the moon passes through the Earth's shadow, it causes the moon to look very unusual for a short period of time. This event is called a lunar eclipse, and it occurs roughly twice a year. https://cdn.kastatic.org/ka-youtube-converted/wuhNZejHeBg.mp4/wuhNZejHeBg.mp4 107 Earth's motions https://www.khanacademy.org/science/up-science-grade-6-revision-course-full-term/x017c12e57b64cfa8:week-4/x017c12e57b64cfa8:untitled-256/e/shadow-and-eclipses 2026-04-07T23:17:37.123726494Z Shadow and Eclipses LO: Shadow and Eclipses Revathi exercise https://www.khanacademy.org/science/teacher-resources-ngss-science-domain/x2811526c37de0eab:hands-on-science-activities/x2811526c37de0eab:middle-school-earth-and-space-science-activities/a/activity-what-happens-during-a-solar-or-lunar-eclipse 2026-02-27T18:00:31.886851552Z Activity: What happens during a solar or lunar eclipse? Make science come alive in your classroom with this free hands-on activity aligned to middle school NGSS standards. article