Milankovitch cycles precession and obliquity | Cosmology & Astronomy | Khan Academy

TL;DR

Earth's tilt and precession, along with other factors, have long-term effects on seasons and climate.

Transcript

We've learned in previous videos that relative to the orbital plane around the sun or the plane of Earth's orbit around the sun, the Earth has a certain tilt. So let me draw the Earth's tilt relative to that orbital plane right over here. So this if this is the orbital plane right over here so we're looking right directly sideways on this orbital p... Read More

Key Insights

• 🔍 Earth's tilt at 23.4 degrees is responsible for the occurrence of seasons.
• ⌛ Changes in Earth's tilt over long periods of time can have significant impacts on climate.
• 💱 Precession, the gradual change in Earth's axis rotation, influences the timing and intensity of seasons.
• 💱 Milankovitch cycles, including changes in tilt and precession, play a role in long-term climate change and the occurrence of ice ages.
• 🥡 Earth's tilt takes around 41,000 years to go from a minimum value to a maximum value and back.
• 🔍 The last maximum tilt occurred around 8,700 BCE, and the next minimum tilt is projected for the year 11,800.
• 🥡 Precession takes approximately 26,000 years to complete one full cycle.

Questions & Answers

Q: How does Earth's tilt affect the seasons?

Earth's tilt causes the Northern Hemisphere to receive more daylight and solar radiation when it is pointed towards the sun, leading to warmer seasons. Conversely, when the Northern Hemisphere is pointed away from the sun, it experiences colder seasons.

Q: How long does it take for Earth's tilt to change from a minimum to a maximum and back?

It takes approximately 41,000 years for Earth's tilt to go from a minimum value to a maximum value and then return to a minimum value.

Q: What are Milankovitch cycles?

Milankovitch cycles refer to long-term changes in Earth's orbit and rotation, including tilt and precession, which are believed to contribute to climate change and the occurrence of ice ages.

Q: How does precession affect Earth's seasons?

Precession causes the direction of Earth's tilt to slowly shift over time. This means that the timing of seasons, relative to Earth's orbit, changes gradually, leading to variations in the intensity and duration of seasons.

Summary & Key Takeaways

• Earth has a tilt of 23.4 degrees relative to its orbital plane around the sun, which causes seasonal variations in the Northern and Southern Hemispheres.

• The tilt can vary between 22.1 and 24.5 degrees over long periods of time, impacting climate and seasons.

• Precession, the gradual change in Earth's axis rotation, also affects the timing and intensity of seasons.