Tuesday September 25, 2012

TuesdaySeptember 25,

2012(Telescopes; HTUW: Alien

Galaxy Parts 2 & 3)

The Launch PadTuesday, 9/25/12

Please pick up your graded work off of the side table as you come in.

spirals

barred spirals

ellipticals

irregulars

30%

10%

60%

10%

large

very large

small or huge

varies

List the four types of galaxies, their relative abundance in the Universe,

and their relative sizes.

The Launch PadTuesday, 9/25/12

Identify

barred spiral galaxy

horsehead dark nebula

Announcements• None Today

Assignment Currently Open

Summative or

Formative?Date Issued Date Due Date Into

GradeSpeed Final Day

Quiz 3 S3 9/14 9/14 9/14 9/28

Lab – Distance and Spacing of

the PlanetsF6 9/17 9/18

Lab – Comparing the Terrestrial and Jovian Planets

F7 9/18 9/19

Quiz 4 S4 9/21 9/21 10/5

??

Recent Events in ScienceHubble Catches Glowing Gas and Dark Dust in a Side-On Spiral

The NASA/ESA Hubble Space Telescope has

produced a sharp image of NGC 4634, a spiral galaxy seen exactly side-on. Its

disk is slightly warped by ongoing interactions with a

nearby galaxy, and it is crisscrossed by clearly defined dust lanes and

bright nebulae.

http://www.sciencedaily.com/releases/2012/09/120924093957.htm

Read all about it!

VideoHow the Universe Works:

Alien Galaxy

Part 2 – Studying the Progress of Galaxies(6:06 – 10:43)

Optical (Visible Light) TelescopesAn optical telescope gathers

and focuses light mainly from the visible part of the electromagnetic

spectrum.

Optical telescopes increase the apparent angular size of distant objects

as well as their apparent brightness.

In order for the image to be observed, photographed, studied, and sent to a

computer, telescopes work by employing one or more curved optical

elements, usually made from glass lenses and/or mirrors, to gather and bring that light to a focal

point.

Optical (Visible Light) Telescopes

The two main types of optical telescopes are:

Refracting telescopes Reflecting telescopes

Refracting Optical TelescopesRefracting telescopes use a lens (called the objective) to

bend (refract) the light to produce an image.Light converges at an area called the focus.

The eyepiece is a second lens used to examine the image directly.

Refracting telescopes have an optical defect called chromatic aberration (color distortion.)

Reflecting Optical TelescopesReflecting telescopes use a concave mirror to gather

the light, and there is no color distortion.Nearly all large telescopes are of this type.

The Andromeda Galaxy using telescopes of different resolution.

The top picture is not “out of focus”, it’s a

resolving issue, not a focus problem.

Optical Resolution

Deployment of the Hubble Space Telescope in Earth Orbit

Figure 23.17

April 24, 1990

Radio Telescopes

Radio wavelength radiation reaches Earth’s surface, so

radio telescopes can be Earth-based.

Radio Telescopes

Radio telescopes are “big dishes” used to gather

radio wavelength electromagnetic

radiation.

Radio TelescopesRadio telescopes have to be very large in order to gather

radio waves, which are about 100,000 times longer than

visible radiation waves.They are often made of a

wire mesh, and have rather poor resolution.

Radio telescopes can be wired together into a

network called a “radio interferometer.”

A steerable radio telescope at Green Bank, West Virginia

Figure 23.15 A

Radio TelescopesRadio telescopes have several advantages over

optical telescopes: they are less affected by weather

they are less expensive to build and maintainthey can be used 24 hours a day

they are able to detect material that does not emit visible radiation

and, they can “see” through interstellar dust clouds

Radio Telescope Images

Microwave Telescopes

The Planck Microwave telescope

The Milky Way as the bright center area, with the

cosmic microwave background left over from the Big Bang shown as the orange mottling at the top and bottom edges of the

image.

Infrared TelescopesThese telescopes capture radiation in the infrared bands of the Electromagnetic Spectrum, therefore they are “seeing”

heat rather than visible light.

Spitzer Infrared Space Telescope

The Helix Nebula in infrared.

Ultraviolet Telescopes

The Hopkins Ultraviolet Telescopes

Our Sun in Ultraviolet

X Ray Telescopes

The Chandra X Ray Observatory

 The supernova remnant Cassiopeia

A in X Ray

Gamma Ray Telescopes

The Fermi Gamma-ray Space Telescope

a gamma-ray image of the entire sky

taken over four days by Fermi

VideoHow the Universe Works:

Alien Galaxy

Part 3 – Black Hole in the Middle of the Milky Way Galaxy

(10:44 – 17:39)