Starry Monday at Otterbein

Astronomy Lecture Series-every first Monday of the month-

June 2, 2008

Dr. Uwe Trittmann

Welcome to

Today’s Topics

• Amateur Astronomy – Inspiration by Observation

• The Night Sky in June

On the Web

• To learn more about astronomy and physics at Otterbein, please visit– http://www.otterbein.edu/dept/PHYS/weitkamp.a

sp (Observatory)

– http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)

Amateur Astronomy - What’s in it for me?

• That depends on you!– Motivation– Interests– Patience– Equipment– Position – …

Personally …• Observing the nightsky inspires me!

– The clearness &he purely colored, tiny spots of light– Looking into infinity…

• Even more intriguing if you can make sense of all that changing glitter

• Like traveling to a different country and wanting to learn more about it

“Two things fill the mind with ever new and increasing admiration and reverence, the more frequently and enduringly the reasoning mind is occupied with them: the star spangled sky over me and the moral law in me.” (I. Kant)

What’s in the Night Sky?

• Constellations: groups of stars, named for apparent vicinity “in” the sky (“on” the celestial sphere)

• Moon: watch the phases of the moon change and its craters, highlands and “oceans”

• Planets: – Saturn’s rings– Jupiter’s cloud bands and Galilean moons– Venus’ phases– Mars’s polar caps

• Deep Sky Objects: Galaxies, clusters, nebulae

Basic Observations in Astronomy• Positions of objects (sun, moon, planets, stars …) • Motion of objects

– with respect to you, the observer- with respect to other objects in the sky

• Changes (day/night, seasons, etc.)• Appearance of objects (phases of the moon, etc.)• Special events (eclipses, transitions, etc.)

All “in the sky”, i.e. on the Celestial Sphere

What’s up in the night sky? The Celestial Sphere• An imaginary sphere

surrounding the earth, on which we picture the stars attached

• Axis through earth’s north and south pole goes through celestial north and south pole

• Earth’s equator Celestial

equator

What’s up for you?

Observer Coordinates

• Horizon – the plane you stand on

• Zenith – the point right above you

• Meridian – the line from North to Zenith to south

…depends where you are!

• Your local sky – your view depends on your location on earth

Look North in

Westerville

Look North on Hawai’i

Star Maps

Celestial North Pole – everything turns around this point

Zenith – the point right above you & the middle of the map

40º90º

That’s what you’d

actually see!

Confusing?

Experts’ view

• Learn to identify crucial constellations

• Find your way around the night sky

At Noon

• Sun at meridian, i.e. exactly south

• Moon setting in the Northwest!

Some hours later

At Sunset

A good starting point• A pair of binoculars and a star map will

keep you busy for a long time – anywhere!– constellations – Planets– Moon– Orion nebula– Andromeda Galaxy– star clusters– Double stars– …

Low End – Naked Eye Astronomy

• Moon phases• Constellations• Identifying planets• Sun set/rise• Rotation of the Earth (daily/seasonal)• Observe changes as you are at your vacation

location• Much more …• Budget: ZERO!

High End – Amateurs contribute to Scientific progress

• Discover– Comets– Asteroids– Exoplanets– Supernovae

• Budget: order $10,000 – Telescope(s)– CCD camera– Location, location, location– Time!

Example: Amateur discovers Exoplanet

Brightness/ time

Otterbein Equipment

• Meade LX200, 10”• Fully computerized, UHTC, electric focuser, etc.

• Celestron 14” telescope

• Celestron 8” telescopes (three)

• digital cameras: Sony DSC-F717, Canon 10D

• and more …

Celestron 8” with solar filter

Celestron 14” in shed

Some “real” astrophotos• With a telescope and the simplest digital camera

you can shoot amazing astrophotos!• You basically use the telescope as a telephoto

lens • Digital cameras supply instant feedback, so the

learning curve is steep!

• Observatory Homepage: http://www.otterbein.edu/dept/PHYS/weitkamp.asp• Photos at: http://www.otterbein.edu/home/fac/uwtrtt/Observatory/BestPhotos.html

Lunar South Pole Region

(Photowith the 14”CelestronandSony DSC F- 717DigitalCamera)

Moon

(Photowith the 8”CelestronandSony DSC F- 717DigitalCamera)

Saturn

(Photowith the 10”LX200 andSony DSC F- 717DigitalCamera)

Saturn and Moons

(Photowith the 10”LX200 andSony DSC F- 717DigitalCamera)

Jupiter with Red Spot

(with C-8Barlow lens &full zoom, Exp. 1/5”,A2.0, seeing worseningfrom coldhaze, just gotlucky )

Jupiter and Moons

(Photowith the 8”CelestronandSony DSC F- 717DigitalCamera)

Orion Nebula (M42/M43)

(Photowith the 10”Meade LX200andSony DSC F- 717DigitalCamera)

Irregular Galaxy (M82)

(photographed with C8, Canon 10D SLR camera, 146 sec exposure, handguided)

     

Dumbbell Nebula (M27)

M11

• Open Star Cluster in Scutum (with Canon 10D)

Classifying Objects

• Sun and Moon• Planets and their moons • Stars and Constellations

– Variable stars• The Milky Way• Deep Sky Objects

– Star Clusters (Open and Globular)– Bright and Dark Nebulae– Galaxies (used to be called nebulae also)

When to observe which Objects

• The surface features on the Moon are best seen when the Moon is not full (nor new )

• Observe Jupiter’s four Galilean moons with binoculars whenever Jupiter’s up

• Small telescope will show Saturn’s rings• Milky Way can be seen under dark skies

(… already in Madison county)

Ecliptic

The tilt of Earth’s axis is responsible for the tilt of the Sun’s apparent path with respect to the celestial equator

Motion of Sun, Moon and other Planets• All major bodies in the Solar System move around ecliptic • Slow drift (from W to E) against the background of stars

Motion of the Moon• Moon shines not by its own light but by reflected

light of Sun Origin of the phases of the moon

• Moon revolves around the Earth

• period of revolution = 1 month

Phases of the Moon (cont’d)

• Moon rotates around earth in one month

• Moon rotates around itself in the same time

always shows us the same side!

“dark side of the moon” (not dark at all!)

Motion of the Planets

• Along the ecliptic as Sun and Moon

• But: exhibit weird, “retrograde” motion at times

The heliocentric Explanation of retrograde planetary motion

See also: SkyGazer

SkyGazer• A computer program that simulates the

vision of the sky during day and night

Things to observe:• Set your position on Earth: observe how view of

sky changes as you move E,W, N,S• Note the distribution of sunlight on Earth!• Rotation is around Polaris which is not in zenith

Inner and Outer Planets

• Inner Planets: closer to sun than Earth– Mercury & Venus– Always close to sun in the sky

• Outer Planets: further from sun than Earth– Mars, Jupiter, Saturn, Uranus, Neptune, Pluto– Best viewing when opposite of sun in the sky

Inner Planets

Inner planet

Earth

superior conjunction

inferior conjunction

western elongation

eastern elongation

Outer Planets

Outer planet

Earth

conjunction

opposition

quadraturequadrature

Close Outer Planet

Outer planet

EarthSize of planet varies a lot as Earth moves

Far-Out Planet

Outer planet

Earth

Size of planet varies little as Earth moves

Deep Sky Objects

• Usually faint and/or small• Best observed under dark skies/ moonless

nights• Some are binocular objects, some require

sizeable telescopes

Deep Sky Objects: Open Clusters•Classic example: Plejades (M45)

•Few hundred stars

•Young: “just born”

Still parts of matter around the stars

Deep Sky Objects: Globular Clusters• Classic example: Great Hercules Cluster (M13)

• Spherical clusters• may contain millions of stars• Old stars• Great tool to study stellar life cycle

From the RooftopPlejades in Taurus,

Open Cluster

M92 in Hercules, Globular Cluster

Deep Sky Objects: Nebulae Classic example: Orion Nebula (M 42)• hot glowing gas

Temperatures ~ 8000K

• Made to glow by ultraviolet radiation emitted by young O- or B-type (hot)

stars located inside

• Color predominantly red, the color of a particular hydrogen emission line (“H”)

Dark Nebulae• Classic Example: Horsehead Nebula in Orion

Trifid Nebula (M20)

Good example for dark dust lanes in front of an emission nebula

Deep Sky Objects: Planetary Nebulae

• Classic Example: Ring nebula in Lyra (M57) (Here: “Eye of God” Nebula)

• Dead, exploded stars• We see gas expanding in a sphere• In the middle is the dead star, a

“White Dwarf”

Eskimo Nebula

Eskimo Nebula: close up

Deep Sky Objects: Galaxies• Classic example: Andromeda Galaxy (M31)

• “Island universes”• Made out of billions

of stars and dust• Very far away (millions of ly’s)• Different types:

– Spiral, elliptic, irr.

Deep Sky Catalogues

• Some of the best deep sky objects can be found in the Messier Catalogue (e.g. M 31)

• Messier (around 1770) catalogued the objects not to confuse them with comets

• There are 110 Messier Objects

• Other catalogues:– NGC: new general catalogue (1880) lists 7800 objects– Caldwell list: 109 best non-messier objects– Herschel 400: from Herschel’s famous list, early 1800’s

The Night Sky in June

• Shortest Nights and EDT => late observing!

• Early summer constellations are up: Virgo, Bootes, Hercules, Serpens Caput, Ophiuchus,

• Mars, Saturn still visible early evening, Jupiter late at night.

Moon Phases• 6 / 3 New Moon

• 6 / 10 (First quarter Moon)

• 6 / 18 (Full Moon)

• 6 / 26 (Last Quarter Moon)

Today at

Noon

• Sun at meridian, i.e. exactly south

10 PM

Typical observing hour, early June

MarsSaturn

Zenith

• Big Dipper points to the north pole

West

• Saturn near Praesepe (M44), an open star cluster

• Oops, that was last year! Now Saturn is here!

East

• Canes Venatici:– M51

• Coma-Virgo Cluster

• Globular Star Clusters– M3, M5

South

Virgo andComa

with the Virgo-Coma

galaxy cluster

Virgo-Coma

Cluster

• Lots of galaxies within a few degrees

M87, M88 and M91

East

– Hercules– Corona

Borealis– Bootes

Globular Star Clusters:• M 3• M 5• M 13• M 92

Low in the South

– Virgo– Corvus– Libra

Globular Star Cluster:

• M 5

Centaurus

M13: Globular ClusterThese guys will know of our existance in 21,000 years!

Mark your Calendars!

• Next Starry Monday: October 6, 2008, 7 pm (this is a Monday )

• Observing at Prairie Oaks Metro Park: – Friday, July 11, 2008, 9:15 pm

• Web pages:– http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.)– http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)