AstrophysicsIntroduction to the Universe

What is it we can see in the sky?

Image source: http://web.eps.utk.edu/research/images/SolarSystem.jpg

Our Solar System

Planets Types of planets:

Jovian - gas planets

Jupiter, Saturn, Uranus & Neptune

Terestrial

Mercury, Venus, Earth, and Mars

protoplanets

celestial objects the size of a moon

exoplanets - Exoplanet Overview

Image Source: http://www.bcssa.org/newsroom/scholarships/great8sci/Photos/Space_Photos/Solar_SystemB.PNG

Astronomical Unit

• When we talk about distances inside the solar system:

• Astronomical Unit (AU) : distance between the Earth & the sun or 93 million miles.

Need to know terms:

• Revolution: how long it takes a planet to go around the sun.

• Rotation: how long it takes a planet to turn once on its axis.

Light Year

• Light Year: the distance light travels in one year or 6 trillion miles

Trivia: The Sun is so far away that

light from the sun takes 8 minutes to reach the Earth, at

LIGHT SPEED.

The Inner Planets

The Outer Planets

What is a galaxy?• Large grouping of stars, gas, and dust in space that are held together by gravity.

• The largest galaxies contain more than a trillion stars. Smaller galaxies may have only a few million.

• Scientists estimate the number of stars from the size and brightness of the galaxy.

Main Types of Galaxies

Spiral

Elliptical

Irregular

Our solar system is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth. Almost everything that we can see in the sky belongs to the

Milky Way Galaxy.

Barred Spiral

Earth in the Milky Way

Our Sun

Our Sun: Extreme Ultraviolet Imaging Telescope (EIT) image of a huge, handle-shaped prominence taken on Sept. 14,1999 taken in the 304 angstrom wavelength - Prominences are huge clouds of relatively cool dense plasmasuspended in the Sun's hot, thin corona. At times, they can erupt,escaping the Sun's atmosphere.

http://www.nasa.gov/multimedia/imagegallery/image_feature_21.html

Before we start exploring, let’s talk about distances

• The distances between most objects in space are huge, and mind boggling.

• Because of the vast distances in space we use 2 measurements.

Our Moon

Moon Aglow: Framed by the Earth's horizon and airglow, the full moon floats in the blackness of space in this photo from the Expedition 10 crew on board the International Space Station.

http://www.nasa.gov/multimedia/imagegallery/image_feature_290.html

StarsLarge body

Made of gas: hydrogen & helium

Gives off light: Nuclear fusion

White Dwarfs: small as Earth

Giants: can be 10 to 1000 times larger than Earth

The galaxy cluster 1E 0657-56 (known as the Bullet Cluster) lies 3.8 billion light-years away. It's one of hundreds that appear to be carried along by a mysterious cosmic flow.

http://www.nasa.gov/centers/goddard/news/topstory/2008/dark_flow.html

Comets

Ablaze with Infrared Light: Siding Spring streaking across the sky, as seen by NASA's Wide-field Infrared Survey Explorer, or WISE. This movie stitches together five frames taken by WISE as it orbited Earth during its ongoing infrared survey of the whole sky. The images span about eight hours of time.

http://www.nasa.gov/mission_pages/WISE/multimedia/pia12836v.html

Asteroids

Spitzer Surveys Dozens of Near-Earth Asteroids: This image, taken by NASA's Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of Eros, an asteroid with an orbit that takes it somewhat close to Earth.

http://www.nasa.gov/mission_pages/spitzer/multimedia/eros.html

Meteors

Perseid Power: This bright and colorful fireball meteor flashed through skies over Japan in the early morning hours of August 12. Ending at the upper right, the meteor's trail points down and to the left, back to the shower's radiant point between the constellations of Perseus and Cassiopeia.

http://www.nasa.gov/multimedia/imagegallery/image_feature_206.html

Hubble Space Telescope

Hubble floating above Earth during servicing mission 3B, March 2002.http://hubblesite.org/the_telescope/hubble_essentials/image.php?image=hst-above

International Space Station

A View From Above: Backdropped by a colorful Earth, this full view of the International Space Station was photographed from the Space Shuttle Discovery during the STS-114 Return to Flight mission, following the undocking of the two spacecraft.

http://www.nasa.gov/multimedia/imagegallery/image_feature_390.html

Astrophysicsthe branch of astronomy concerned with the

physical and chemical properties of celestial bodies

Image source: Terrestrial Planets Interiors - http://www.nasaimages.org/

Terrestrial Planets and Moons

Image source: Gas Giant Interiors - http://www.nasaimages.org/

Jovian Planets and Moons

Image source: Moons of the Solar System - http://www.nasaimages.org/

What’s in our Solar System?

1 Sun8 Planets ( 170 Moons)

5 Dwarf Planets1 Asteroid Belt

Various Comets

MeteoroidsAsteroids

Left over debris (Kuiper Belt)

Introduction to the UniverseE.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellation

Image Source: http://kepler.nasa.gov/multimedia/AnimationsandMore/animations/?ImageID=36

•M80 (NGC 6093), •147 known globular star

clusters in the Milky Way galaxy.

•about 28,000 light-years away•hundreds of thousands of stars, •about 15 billion years old• range of stellar masses. •more highly evolved than, or in

a few rare cases more massive than, our own Sun.

•bright red giants, nearing the ends of their lives.

Globular Cluster

Introduction to the UniverseE.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellation

Image Source: http://spacetelescope.org/images/heic0603b/

•NGC 265 in the Small Magellanic Cloud.

•The image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope

•The brilliant open star cluster, NGC 265, is located about 200,000 light-years away and is roughly 65 light-years across.

•similar age and chemical composition, the effects of other stellar properties are more easily determined than they are for isolated stars.

Open Cluster

Introduction to the Universe

• Constellations

• Historically speaking - pattern in the sky with a pattern

• Modern beliefs - internationally defined area of the celestial sphere

• Stellar Clusters - very useful in studying stellar evolution

• Open Cluster - similar age and chemical composition

• Globular clusters - have the same age but cover a range of stellar masses.

E.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellation

Introduction to the Universe

What is a light year?

The distance light travels in a vacuum in one Julian year. (365.25 days)

exactly 9,460,730,472,580.8 km

about 5,878,625,373,183.608 miles (about 6 trillion miles)

about 63,241.1 astronomical units

about 0.306601 parsecs

E.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellationE.1.3Define the light year

AstrophysicsIB Physics HL

Dublin Jerome High SchoolC. Crawford

So how do we start to understand the

universe

Understanding the places and distances

Introduction to the UniverseE.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellationE.1.3Define the light yearE.1.4Compare the relative distances between stars within a

galaxy and between galaxies, in terms of order of magnitude

It is important for us to know what else there is beyond our solar system

• In order to do that, there must be a way to replicate measurements

• In order to do that we have to make ourselves a system of identification

Introduction to the Universe

closest star -

Alpha Centauri, located about 4.37 light years away (41.5 trillion km).

closest planet - HD 189733b - 63 ly from sun

status of the voyager 1 and 2

E.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellationE.1.3Define the light yearE.1.4Compare the relative distances between stars within a galaxy and between galaxies, in terms of order of magnitude

Introduction to the Universe

Read “Mask of the Black god”

E.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellationE.1.3Define the light yearE.1.4Compare the relative distances between stars within a galaxy and between galaxies, in terms of order of magnitude

E.1.5Describe the apparent motion of the stars/constellations over a period of a night and over a period of a year, and explain these observations in terms of the rotation and revolution of the Earth

Introduction to the Universe

• celestial sphere

Introduction to the UniverseE.1.1Outline the general structure of the solar systemE.1.2Distinguish between a stellar cluster and a constellationE.1.3Define the light yearE.1.4Compare the relative distances between stars within a

galaxy and between galaxies, in terms of order of magnitude

•View the Milky Way at 10 million light years from the Earth.

•Then move through space towards the Earth in successive orders of magnitude until you reach a tall oak tree just outside the buildings of the National High Magnetic Field Laboratory in Tallahassee, Florida.

•After that, begin to move from the actual size of a leaf into a microscopic world that reveals leaf cell walls, the cell nucleus, chromatin, DNA and finally, into the subatomic universe of electrons and protons.

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html

What else is it we can see

in the sky?

Galaxies!!!

Objects in the sky

•collection of a very large number of stars

•mutually attracting each other through the gravitational force

•stay together

•number of stars varies between a few million and hundreds of billions.

•There approximately 100 billion galaxies in the observable universe.

Galaxies

Objects in the sky

Spiral galaxies consist of a rotating disk of stars

and interstellar medium

along with a central bulge of generally older stars.

Extending outward from the bulge are relatively bright arms.

Galaxies - Spiral

Image Source: http://www.spacetelescope.org/images/potw1006a/

The Milky Way Galaxy

Our Sun is just one out of over 200 billion stars in our galaxy, the Milky Way. The Sun is located in the Orion arm of our galaxy about 25,000 light years from the center of the Galaxy. Kepler will be examining over 100,000 stars in our neighborhood of our galaxy in the Cygnus and Lyra constellations. Most of these stars will be somewhere between 500 and 3,000 light years from our solar system.

http://kepler.nasa.gov/multimedia/AnimationsandMore/animations/?ImageID=36

Objects in the sky

Elliptical cross-section and no spiral arms.

They range in shape from nearly spherical to highly flattened ellipsoids

size from hundreds of millions to over one trillion stars.

In the outer regions, many stars are grouped into globular clusters.

Galaxies - Elliptical

Image Source: http://www.calvin.edu/academic/phys/observatory/images/Astr110.Fall2005/

Feyen.html

Objects in the sky

Irregular galaxies have no specific structure.

The Large and Small Magellanic Clouds, the nearest galaxies

Image to the right is known as the Bird Galaxy

Galaxies - Irregular

Image Source: http://anneminard.com/2009/04/05/day-72-galaxies-of-salt-and-other-stellar-teaching-moments-from-huntsville-alabama/

AstrophysicsNebulae

Objects in the sky

•Nebula is an interstellar cloud of dust, hydrogen gas and plasma.

It is the first stage of a star's cycle but it can also refer to the remains of a dying star (planetary nebula).

Originally nebula was a general name for any extended astronomical object,

Nebulae often form star-forming regions, such as in the Eagle Nebula.

Nebulae

Nebulae