1.18 Astro 1 Section 1

1.18 Astro 1 Section 1 - Astro 1 Section 1 Professor Brandt...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Astro 1 Section 1 Professor Brandt Monday January 18th 1999 Announcements: Lecture notes: Class 4. Earth has a 13 mile equatorial bulge due to its rotation Last time we learned about rotation axis of the Earth and how it is tipped by 23.5 degrees from the plane of Earth's orbit around the sun. The north pole points towards a star in the sky called Polaris However there is a subtle point that we missed last time. It turns out that the rotation of the Earth actually wobbles around very slowly. Like a gyroscope -- if you have played with a gyroscope you know the motion of the gyroscope keeps it relatively stable but does wobble some due to the Earth's gravity trying to pull the gyroscope over. A similar effect occurs for Earth - gravity of sun and moon tugs on Earth's equatorial bulge and this causes slow precession. Noticed over 2000 years ago Hipparchus who compared star positions over 200 years Very slow process - 1 cycle takes 26000 years 4800 years ago Thuban was the north star according to Egyptian records
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/20/2008 for the course ASTRO 1 taught by Professor Brandt during the Spring '99 term at Penn State.

Page1 / 2

1.18 Astro 1 Section 1 - Astro 1 Section 1 Professor Brandt...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online