Download Week Two

Exploring the Big
Picture through the
Hubble Space
Telescope
WEEK TWO: STAYING CLOSE TO HOME
Date: September 23, 2013
Instructor: Robert Arn
Email: [email protected]
Website: AstroArn.com
Our Incredibly Large and Minuscule
Solar System

1 Lightyear (ly) = 9.46x10^15 meters

Distance to nearest star = 4.2ly (Proxima Centaur)

Diameter of Milky Way Galaxy = 110,000ly

Diameter of Solar System = 0.0006ly = 40AU = 15000 Earth-Moon
Distances

1AU = 149,597,871km = max(Earth-Sun Distance)
Content of Solar System

Sun: 99.85%

Planets: 0.135%

Comets: 0.01%

Satellites: 0.0005%

Minor Planets: 0.0000002%

Meteoroids: 0.0000001%

Interplanetary Medium: 0.0000001%
What is a planet

Three properties

A celestial body that is in orbit around the sun

Has sufficient mass for its self-gravity to overcome rigid body forces so
that it assumes a hydrostatic equilibrium (nearly round) shape and

Has cleaned the neighborhood around its orbit

In our solar system the planets lie on same plane and travel in same
direction around Sol

Terrestrial – Mercury, Venus, Mars, Earth

Jovian – Jupiter, Saturn, Uranus, and Neptune
Venus

Only imaged once

Image is false color to enhance clouds

Sulfuric Acid clouds instead of water-vapor

Clouds permanently shroud volcanic surface

Much better target for spacecraft/satellites
Radius: 3,760 miles
Surface Area: 177.7 million sq miles
Mass: 0.815 Earth Mass
Sun Distance 67,240,000 miles
Mars

Every 26 months
Mars is opposite
the Sun

Since 1993 this has
happened 9 times

Angular size is
actual size
photographically

Hubble has not
imaged Mars since
2005

Massive storms
(2005) cause the
planet to change
over hours/days
Radius: 3,396 km
Surface Area:
144,798,500 sq. km
Mass 0.107 Earth Mass
Sun Distance:
206,669,000km
Saturn

Saturn’s rings tilt every 30 years

When edge on 4 moons pass in front of
the planet (relative to Earth)

Hubble images found 7 new moons
(from 11)

Currently 53 moons have been
discovered

Titan – the largest moon – effects the
orbit of other moons

Best chance of life in the solar system
Radius: 36,184 miles
Surface Area: 16.5 billion sq. miles
Sun Distance: 890,700,000 miles
Mass: 95.16 Earth Mass
Uranus

Uranus was discovered
to have rings in 1977

They tilt every 84 years

At poles 42yr night +
42yr day

Hubble was able to
image rings edge-on in
2007

In ‘98 Hubble found
different layers of clouds
Radius: 15,759 miles
Surface Area: 3.121 billion sq. mi
Mass: 14.5 Earth Mass
Sun Distance: 2.9 billion km
The false colors in this image indicate
altitude.
The green and blue regions show where the
atmosphere is clear, allowing sunlight to
penetrate deep into Uranus.
In the yellow and gray regions, a haze or
cloud layer is reflecting sunlight away.
Orange and red colors indicate very high
clouds, like cirrus clouds on Earth. These
move near 560 mi/h
Neptune

High altitude clouds of methane ice

Seasons like Earth due to 29 degree tilt
(23 on Earth)

About 30 moons known to orbit
Radius: 15,299 miles
Surface Area: 2.941 billion sq miles
Mass: 17.14 Earth Mass
Sun Distance: 4.5 billion km
What is a dwarf planet


Four properties

A celestial body in orbit around the sun

Has sufficient mass for its self-gravity to overcome rigid body forces so
that it assumes a hydrostatic equilibrium (nearly round) shape

Has NOT cleaned the neighborhood around its orbit

Is NOT a satellite (moon)
All other objects (except satellites) orbiting the sun are called small
solar system objects
Pluto

Hubble has produced the most detailed image of Pluto to date

Taken from 2002 to 2003

Took 4 years and 20 computers operating continuously to produce these images

Cannot see craters or mountains (if exist) but does see different color terrain

Sun breaks up solid methane leaving residue

New Horizons

P4 (Kerberos) was
discovered in 2011 after the
new WFC3 was installed

P5 (Styx) was discovered in
2012 and is 10-20km in
diameter

Both are thought to of
formed by merging material
after collisions with Pluto

All moons discovered by
Hubble
Radius 1161 km
Surface Area: 1,665,000 sq km
Mass: 0.00218 Earth Mass
Sun Distance 7,311,000,000 km
Ceres: Asteroid/Dwarf Planet
Took 267 images
Discovered nearly as spherical as Earth
580 miles diameter – largest known
asteroid
Discovered in 1801 in belt between Mars
and Jupiter – possible failed planet
Contains 1/3 of mass of belt
Dawn spacecraft - 2015
Planetary Impact Threat

Besides the planets comets, asteroids, and various interplanetary
debris make up the solar system

Most of this is harmless to us on Earth

Each year over 10,000 tons of meteor fall to Earth from space

If the particles are big enough (the size of a grain of sand) we can see it

During meteor showers, the material that
falls to Earth is left over from the dust tail of
comets

Sporadic meteors

Comets are composed of mainly rock and
ice

Solar wind + radiation blows on comets
and produces tails

These tails can be as large as 93 million
miles (Earth-Sun distance)

About once every 5 years a comet gets
bright enough/close enough to see naked
eye

Many more can only be seen with
telescope

There are trillions of comets with a nucleus
greater than 1km

Most are past Neptune and most will stay
there


Collisions
Fate of most comets

Fall into sun

Exit the solar system

Large orbit – Jupiter perturbation – Comet
Halley-Bopp
Comet Lovejoy by Luis Argerich
Displayed with permission
Comet ISON – Imaged by Hubble when still beyond Mars orbit
May turn into a naked eye comet in the next few months
Event of the Century (or less)

1993 working at Palomar David Levy, Carolyn Shoemaker, and
Eugene Shoemaker discovered Comet SL9

Process of finding Comets/Asteroids/Meteors


Messier sidenote
In order to figure out the path of an object several observations at
high resolution are needed

1) Found to be orbiting Jupiter – not the sun

2) 1992 July – passed really close to Jupiter breaking it up

3) May ‘93 – discovered it would collide in ‘94

All impacts on night side

Thankfully Jupiter rotates every 10 hours

Hubble counted 21 fragments 2 months prior

Thanks to dust clouds, size and composition were unknown

Rubble pile – no fireball

Huge – tunnel through atmosphere then explode produce fireball

Solid – tunnel through atmosphere then nothing

Typically Hubble images are routinely downloaded and processed
at a later date by one or two individuals

Many scientists gathered around to watch the data come in (raw
and unprocessed form

1km comet produced Earth sized
hole in Jupiter atmosphere

Each impact was equal to 1 million
Hiroshima bombs

Fireball reached over 1km high and
fireball remained for 90 minutes

From Hubble images, learned
about composition of comet and
atmosphere of Jupiter

Produced dark center core with
inner ring and outer crescent
The Good and The Bad

The Good


Jupiter is a very large target. Mass is great enough to significantly effect
all objects in solar system
The Bad

If one fragment of this comet hit earth – extinction level event


65 million years ago a 10km asteroid killed off the dinosaurs and 60% of life on
Earth
Even smaller strike would kick up enough dust in atmosphere to
dramatically effect climate change
Crater Tycho – Hubble Image

Over 183 confirmed meteor
impacts on Earth

Most are old enough to
been effected by Earth’s
changing surface

In Mars/Jupiter asteroid belt
– Kuiper Belt many asteroids
100s km in size

On average 1km size
impact every 100,000 years

Prior to SL9 the problem of Earth impacts was left to 6-10 people

Now multiple surveys

As of September 17, 2013


10217 NEO have been discovered

859 are asteroids with a diameter larger than 1km

1423 are classified as Potentially Hazardous Asteroids (PHAs)
None currently discovered will collide w/ us in next 200 years
www.spaceweather.com

July 23rd, 2012
amateur
astronomer
Anthony Welsey,
discovered a new
dark spot on
Jupiter

This was result of
another comet –
much larger than
SL9 - striking
Jupiter

No one saw this
one coming…
Exoplanets

In 2007 Gemini North (Keck Telescopes) was the
‘first’ to directly image a planet around a star
other than our own

HR 8799 located 130 light-years away

Before this, only indirect techniques were used

This planet is at least 7 times the mass of Jupiter
and about the same diameter

After the position was known, the planet was
found in data from Hubble (left) taken in 1998

July 11, 2013 Hubble identified
first ‘blue’ planet of a giant
Jupiter-sized planet located 63
light-years away

It has 4,500-mile-per-hour winds
that are so hot the melt
silicates into raindrops of
molten glass (this is where the
blue comes from – not
oceans)

Hubble now (after SM5) has
the ability to determine the
atmosphere of some
exoplanets