1.15 Astro 1

1.15 Astro 1 - Question 3 - What causes seasons? What makes...

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 Friday January 15th 1999 Announcements: Lecture notes: Four Basic Important Questions Why day and night? What causes the seasons? Why different stars in summer and winter? What makes phases of moon? Four Basic Important Facts Earth orbits sun in 1 yr Earth rotates in 1 day Rotation axis tilted from plane of orbit by 23.5 degrees Moon orbits Earth in about 27.3 days Title of today's lecture is Darkness and Light Winter and Summer discuss and answer 5 basic but important questions To answer them we will frequently use 4 important facts Question 1 - Why day and night? Circumpolar rotation = the stars appear to move around a particular star called the North Star (Polaris) during course of night Point out Big Dipper and pointer stars Little Dipper and Polaris Arcturus - students name it Takes 24 hours - 24 hour rotation of Earth What would sky at North Pole look like - pointer stars still point to Polaris
Background image of page 1

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

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

Unformatted text preview: Question 3 - What causes seasons? What makes days longer in summer than in winter? Use fact #3 - rotation axis is tilted from orbital plane by 23.5 degrees Earth's rotation vector points towards Polaris and is fixed there Changes angle at which sun's rays strikej different parts of Earth's surface Extreme of North Pole and South Pole In far North during summer doesn't get dark at all. Seasons produced by combination of tilt of Earth's axis and the revolution about the sun. No tilt = no seasons Summer solstice is June 21 = longest daylight of year in far Northern hemisphere Winter solstice = December 21 = shortest daylight of year in far Southern hemisphere Fall and spring equinoxes Spring equinox = March 21 Autumn equinox = September 23 Why different stars in summer and winter? Can't see stars located behind sun. Phases of Moon not Earth blocking sunlight from Moon - this only happens during eclipses...
View Full 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

1.15 Astro 1 - Question 3 - What causes seasons? What makes...

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