Transcript Precession nutation barycenter pptx

Warm up
• Kahoot questions
Create a 3 door foldable for your notes
• Title the doors: Precession, Nutation, Barycenter
Precession
• The Earth's axis rotates (precesses) just as a spinning top does. The
period of precession is about 26,000 years.
• Precession is caused by the gravitational pull of the Sun and the
Moon on the Earth.
• The result is that the North Pole will not always point towards the
same starfield.
• While the Pole Star in the northern hemisphere is now Polaris, in
3000 B.C., the north celestial pole coincided with Thuban, a star in
the constellation of Draco. In 14,000 A.D. (or in around 11,000 years)
Vega, in Lyra, will be the northern pole star.
Precession
• No change in tilt of axis
• No affect on seasons
Nutation
• wobbling around the precessional axis
• There is a change in the tilt of Earth’s axis ½ degree one way or the
other
• Occurs approximately every 18 years
• Caused by the moon
• Slightly affects the seasons because there is a change in the tilt of
Earth’s axis
Barycenter
• the center of mass of two or more bodies that are orbiting each
other, or the point around which they both orbit.
Do you think the center of mass is nearest the larger object, or smaller
object?
Barycenter continued
• it is the center of mass where two or 3 more celestial bodies orbit each
other. When a moon orbits a planet, or a planet orbits a star, both bodies
are actually orbiting around a point that lies outside the center of the
primary (the larger body).
• For example, the moon does not orbit the exact center of the Earth, but a
point on a line between the Earth and the Moon approximately 1,710 km
below the surface of the Earth, where their respective masses balance. This
is the point about which the Earth and Moon orbit as they travel around
the Sun.
• • Also, the Sun is not stationary in our solar system. It actually moves as
the planets tug on it, causing it to orbit the solar system's barycenter. The
Sun never strays too far from the solar system barycenter.
Precession, nutation, barycenter lab
• Obtain materials as directed-when the music starts
• No horseplay. Horseplay will result in -10 points or more from the lab
grade, continued horseplay will result in a 0.
• Listen to instructions
• Noise level should be BELOW music
• Stay on task-we have limited time to complete labs
• When you finish, clean up any trash off the floor and table, return
supplies where you got them
• You have until 5 minutes before the bell to complete the lab so work
quickly. You must not pack up without permission.
Closure:
• 1. ) In 11,000 years, the earth’s axis
will point to the star Vega instead
of the North Star as it does now.
The reason for this is:
• A. Precession
• B. Nutation
• C. Barycenter
• D. Elliptical orbits
2. T/F The moon causes a change in
the angle of Earth’s axis over a
period of 18 years.
3. This change of the angle of Earth’s
axis caused by the moon, is called
_________________________.
4. The sun is not stationary in our
solar system, but orbits the solar
system’s
_____________________________.