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

Info icon This 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
Image of page 1

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

View Full Document Right Arrow Icon
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

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern