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Astronomy/Geology 330 Seminar on Asteroids Tuesdays 4-7 pm Kendade Hall 203 Tom Burbine [email protected] Focus of Class Asteroids Comets Meteorites My Background BS in Physics from RPI MS in Geology and Planetary Science from the Univ. Pittsburgh PhD in Planetary Science from MIT

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Astronomy/Geology 330Seminar on AsteroidsTuesdays 4-7 pmKendade Hall 203Tom [email protected]


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Focus of Class

  • Asteroids

  • Comets

  • Meteorites


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My Background

  • BS in Physics from RPI

  • MS in Geology and Planetary Science from the Univ. Pittsburgh

  • PhD in Planetary Science from MIT

  • Postdoc at the Smithsonian’s Natural History Museum for 3 years

  • Postdoc at NASA’s Goddard Space Center for 2 years

  • Researcher at Mount Holyoke since January

  • Taught Astronomy 100 at UMASS in Spring


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Tuesdays in October and November

4-5 pm

Kendade Hall 305

Mount Holyoke College

Introduction to Planetary Science Seminar Series

October 18th – Cometary Volatiles – William Irvine (UMASS)

October 25th – Cometary Dust and Nuclei – Martha Hanner (UMASS)

November 1st – Minor Planet Center – Timothy Spahr (CFA)

November 8th – Asteroid Hazards – Richard Binzel (MIT)

November 15th – NEAR-Shoemaker Mission– Louise Prockter (APL)

November 29th – Deep Impact– Lucy McFadden (Univ. Maryland)

For more information, contact Tom Burbine ([email protected])

Funded by a grant from Mount Holyoke’s Innovation Fund


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Website

  • www.mtholyoke.edu/courses/tburbine/ASTR330

  • Can be accessed using WebCT

  • All presentations will be available on website immediately after class

  • So you don’t have to copy down everything I put up


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Grading

  • Class Exercises - 10%

  • Problem Sets -10%

  • Class Participation - 10%

  • Class Presentation - 10%

  • Mid-Term (October 4th) - 20%

  • Final - 20%

  • Final Project- 20%

  • Late Class Exercises and Problem Sets will have 10% of their grade deducted for every day they are late (unless this is your first class)


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  • A 92.50 - 100

  • A- 89.50 – 92.49

  • B+ 87.50 – 89.49

  • B 82.50 – 87.49

  • B- 79.50 – 82.49

  • C+ 77.50 – 79.49

  • C 72.50 – 77.49

  • C- 69.50 – 72.49

  • D+ 67.50 – 69.49

  • D 62.50 – 67.49

  • D- 59.50 – 62.49

  • ? below 59.49


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Books

  • All books are on reserve in the library

  • Asteroids II

  • Asteroids III

  • Comets II

  • Comet Science

  • The New Solar System


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Office Hours

  • Thursdays 2-4 pm

  • Drop in anytime if you have problem

  • IM or email me anytime if you have problem


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Today

  • 4-5 pm Asteroids, Comets

  • 5-6 pm Meteorites

  • 6-7 pm Students introduce themselves

  • 10 minute break between classes

  • We will have lots of definitions today


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What’s the difference?

  • Asteroids

  • Comets

  • Meteorites


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What’s the difference?

  • Asteroids - small, solid objects in the Solar System

  • Comets - small bodies in the Solar System that (at least occasionally) exhibit a coma (or atmosphere) and/or a tail

  • Meteorites - small extraterrestrial body that reaches the Earth's surface



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Why are these things important?

  • These things can hit us (and possibly kill us)

  • They are records of the early solar system

  • They could be sources of material for mining



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Probability

  • Probability of Impact


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Record of Early Solar System

  • Meteorites usually have ages of ~4.6 billion years

  • Asteroids and comets are thought to be the building blocks of the terrestrial planets


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Resources

  • In outer space, it may be easier (and less expensive) to extract raw materials from asteroids or comets then to bring them from Earth

  • Raw materials include water, iron, aluminum, chromium


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Problem Set #1

  • Due next week

  • It can be found on the syllabus part of website

  • Problem Set #1


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Meaning of Asteroid

  • Asteroid means “star-like”

  • Called vermin of the sky by astronomers


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Asteroid Flyby

  • Movie

  • Images of 2002 NY40 on August 15-16

  • Asteroid has diameter of 700 meters

  • 524,000 kilometers from Earth (1.3 times the distance of the Earth to the Moon)

  • Movie over 2 hour time period


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951 Gaspra

  • 17 kilometers long, 10 kilometers wide


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433 Eros

  • Surface of 433 Eros

  • Landing of NEAR-Shoemaker on Eros


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When were these objects first discovered?

  • Comets have been known since the earliest days of mankind

  • Usually thought to be unlucky

  • Attacks by heavenly beings on terrestrial people

Comet Ikeya-Zhang

153P/Ikeya-Zhang

Period of 341 years


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Halley’s Comet

  • Edmund Halley figured out that the orbit of the comet of 1682 was nearly the same as those of two comets which had appeared in 1531 and 1607

  • Halley concluded that all three comets were in fact the same object returning every 76 years

  • Halley predicted its return for 1757.

  • Halley's prediction of the comet's return proved to be correct, although it was not seen until December 25, 1758


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Titius-Bode Law

  • The mean distance a (AU) of the planet from the Sun:

  • a = 0.4 + 0.3 x k

  • where k=0,1,2,4,8,16,32,64,128 (0 followed by the powers of two)

  • 1 astronomical unit (AU) is the average distance from the Earth to the Sun


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So …

  • Baron Franz Xaver von Zach organized a group of 24 astronomers to search the sky for the "missing planet"

  • But the first asteroid, 1 Ceres, was not discovered by a member of the group, but rather by accident in 1801 by Giuseppe Piazzi


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But …

  • Three other asteroids (2 Pallas, 3 Juno, 4 Vesta) were discovered over the next few years (1802-1807)

  • After eight more years of fruitless searches, most astronomers assumed that there were no more

  • However, Karl Ludwig Hencke persisted, and began searching for more asteroids in 1830.

  • Fifteen years later, he found 5 Astraea, the first new asteroid in 38 years. He also found 6 Hebe less than two years later.


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Meteorites

  • Many early cultures recognized (or believed) certain stones as having fallen from the sky

  • Many early cultures had tools made from iron meteorites

  • But for most scientists at the time, stones falling from the heavens were considered superstition or heresy


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More evidence …

  • In 1492, a meteorite weighing almost 130 kilograms landed near the town of Ensisheim, Alsace, France, then in the hands of Germany


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Then ..

  • In 1794, Ernst Friedrich Chladni, considered the father of meteoritics, published a book in which he concluded that stone and iron masses did fall out of the sky

  • In 1803, thousands of meteorite fragments bombarded L'Aigle in Normandy, France, an event investigated by Jean-Baptiste Biot of the French Academy of Science.


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Thomas Jefferson

  • Meteorite landed in Weston, CT in 1807

  • It was brought to Yale where it was concluded it was from outer space

  • Thomas Jefferson, President of the United states, was told about it


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And responded

  • "Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven."


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How are these objects named?

  • Asteroids

    • After being observed on two consecutive nights, the object is given a provisional designation

    • a 4-digit number indicating the year

    • a space

    • a letter to show the half-month

    • another letter to show the order within the half-month

    • And an optional number to indicate the number of times the second letter has been repeated in that half-month period.

  • For example, 1977 RG


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Half Month Discovery

  • Letter Dates Letter Dates

  • A Jan. 1-15 B Jan. 16-31

  • C Feb. 1-15 D Feb. 16-29

  • E Mar. 1-15 F Mar. 16-31

  • G Apr. 1-15 H Apr. 16-30

  • J May 1-15 K May 16-31

  • L June 1-15 M June 16-30

  • N July 1-15 O July 16-31

  • P Aug. 1-15 Q Aug. 16-31

  • R Sept.1-15 S Sept.16-30

  • T Oct. 1-15 U Oct. 16-31

  • V Nov. 1-15 W Nov. 16-30

  • X Dec. 1-15 Y Dec. 16-31

  • I is omitted and Z is unused


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Order within Month

  • A = 1st B = 2nd C = 3rd D = 4th E = 5th

  • F = 6th G = 7th H = 8th J = 9th K = 10th

  • L = 11th M = 12th N = 13th O = 14th P = 15th

  • Q = 16th R = 17th S = 18th T = 19th U = 20th

  • V = 21st W = 22nd X = 23rd Y = 24th Z = 25th

  • I is omitted


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Asteroids discovered between Sept 16-30 of 1995

  • 1995 SA

  • 1995 SB

  • ...

  • 1995 SY

  • 1995 SZ

  • 1995 SA1

  • 1995 SZ1

  • 1995 SA2

  • ...

  • 1995 SZ9

  • 1995 SA10


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Asteroid Numbers and Names

  • When well-observed, asteroid is given a number

  • 5159 1977 RG

  • When was it discovered?


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Asteroid Numbers

  • When well-observed, asteroid is given a number

  • 5159 1977 RG

  • When was it discovered?

    • 1977

    • R Sept.1-15

    • G 7th asteroid


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Asteroid Names

  • Then the discover gets to name it for period of 10 years or so

  • 5159 1977 RG

  • Was named


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Asteroid Names

  • Then the discover gets to name it for period of 10 years or so

  • 5159 1977 RG

  • Was named

    • 5159 Burbine


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Comets

  • Usually named after discoverer (or person who computed its orbit)

  • Comet Halley

  • Number given when discover (or discoverers) have discovered numerous comets

  • Comet Shoemaker-Levy 9


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Comets

  • Comets are now initially designated by the year of their discovery

  • followed by a letter indicating the half-month of the discovery

  • and a number indicating the order of discovery

  • Example, the fourth comet discovered in the second half of February 2006 would be designated 2006 D4.


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Prefixes

  • Prefixes are also added to indicate the nature of the comet

  • P/ - periodic comet (seen two separate times)

  • C/ - non-periodic comet

  • X/ - no reliable orbit could be calculated

  • D/ - a comet which has broken up or been lost

  • A/ - an object that was mistakenly identified as a comet, but is actually an asteroid


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Types of Comets

  • Short period comets – periods < 200 years

  • Long-Period Comets – periods > 200 years


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Also

  • After their second observed perihelion passage, periodic comets are also assigned a number indicating the order of their discovery.

  • Perihelion is the point where an object is closest to the Sun


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So

  • Halley's Comet, the first comet to be identified as periodic, has the systemic designation 1P/1682 Q1 (or 1P/Halley)

  • Comet Hale-Bopp's designation is C/1995 O1


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Comets

  • Comet West

  • Blue tail –gases, white tail – dust particles


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Comet Halley

  • Giotto image

  • Dimensions - 16 x 8 x 8 km


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Image from Deep Impact

  • Comet Tempel 1 or Comet 9P/Tempel 1


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Comets

  • Called Dirty Snowballs by Fred Whipple

  • Because they are mixtures of ice and dust



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