the solar system - uvicvenn/a201/a201-week3.pdf · surrounds the solar system. the voyager team...

The Solar System

Friday, September 20, 2013

The Solar System The Solar System as a life bearing habitat. The Sun The Terrestrial worlds The Jovian worlds The Grand Tour: Voyager and Pioneer The outer solar system: TNOs, the Kuiper Belt, the Oort

Cloud The Habitable Zone The creation of the Solar System


The Sun


The Sun The Sun is a star at the centre of the

Solar System.



Solar System. The Sun contains 99.86% of the mass

of the Solar System




of the Solar System The Sun is composed of hydrogen

(74%), helium (25%) and trace elements.






The surface of the Sun is called the photosphere.







The Sun is powered by nuclear fusion reactions occurring in its core (hydrogen fuses into helium).







The Sun is powered by nuclear fusion reactions occurring in its core (hydrogen fuses into helium).

In addition to light, the Sun emits a stream of energetic particles into space - the solar wind.


The Planets


Distances to the planets

Planet Mean distance (AU) Light travel timeMercury 0.39 3 minutesVenus 0.72 6 minutesEarth 1.00 8 minutesMars 1.52 12 minutesJupiter 5.20 42 minutesSaturn 9.54 1 hour 16 minutesUranus 19.14 2 hours 33 minutesNeptune 30.06 4 hoursPluto 39.53 5 hours 20 minutes

The physical distance between the Earth and Sun is 148 million km. This distance is defined as 1 astronomical unit (AU).Speed of light is 3 x 105 km/s.


Opening Scene to “Contact” (1997)

Discuss precision versus impression.


Solar energy received by the planets

Planet Relative energy flux

Mercury 6.6Venus 2.0Earth 1.0Mars 0.44Jupiter 0.036Saturn 0.01Uranus 0.003Neptune 0.001Pluto 0.0006

The Earth receives 1378 W of solar energy per square metre. This energy powers our weather and almost all life on Earth.


The Terrestrial Worlds

The rocky planets show a number of similar characteristics: they are all approximately Earth-sized, they are made of dense, rocky material (silicates) and they possess few if any moons.

They differ in terms of their atmospheres, surface temperatures, magnetic fields and geology.


The Terrestrial WorldsPlanet Atmosphere Magnetic

fieldSurface temperature

Geology

Mercury ✘ ✘ 650K (100K) ✘Venus ✔ ✘ 737K ✔

Earth ✔ ✔ 293K ✔

Mars ✘ ✘ 210K ?


Half way through its mission, Curiosity became the first rover to drill into Martian rock and lived up to its name by satisfying one of the biggest mysteries of Mars – could the planet ever have supported life? The answer, according to the US National Aeronautics and Space Administration (Nasa), is an unequivocal “yes”.

Ancient Mars would have had the right chemistry to support life. Curiosity found carbon, hydrogen, oxygen, phosphorus and sulphur – the key organic elements necessary for life on Earth – and, most crucially of all, there was once abundant running water on the surface of the Red Planet, said John Grotzinger, the project scientist.

News from the Mars Curiosity Rover


This set of three images shows views three seconds apart as the larger of Mars' two moons, Phobos, passed directly in front of the sun as seen by NASA's Mars rover Curiosity. Curiosity photographed this annular, or ring, eclipse with the telephoto-lens camera of the rover's Mast Camera on Aug. 20, 2013, the 369th Martian day, or sol, of Curiosity's work on Mars

NASA Mars Rover Views Eclipse of the Sun by Phobos

News from the Mars Curiosity Rover


In the News


The Jovian Worlds

T = 165 K 134 K 76 K 72 K

All have vast magnetic fields, are massive, and gaseous. All have rocky and icy moons.


The Jovian Moons


Giant dust ring around Saturn

What makes the rings of Saturn?


Enceladus continually replenishes the E-ring


Voyager 2: The Grand Tour Voyager 1 & 2 are NASA flyby missions

launched a month apart in 1977. Using a favourable configuration of the

Jovian planets they were designed to “slingshot” around each world to perform a Grand Tour of the outer Solar System.

Voyager 1 & 2 visited Jupiter (1979), Saturn (1981), Uranus (1986) and Neptune (1989).

Voyager 2 carried high resolution cameras that provided stunning close-ups of the Jovian worlds.

Voyager 1 travelled past the very edge of the Solar System to interstellar space in late August 2013.


Voyager 2: The Grand Tour

Voyager Grand Tour 15-m movie

What would you update on this video?


Voyager fly by

today - outer solar system & formation of the solar system


The outer solar system

Neptune is the last Jovian world as we head further out.

The discovery of Eris in 2005 (about same size as Pluto, but slightly more massive) forced astronomers to reconsider the term planet. dwarf planet (many other terms too) also Ceres in the inner solar system

Pluto, Eris and thousands of other small bodies make up the Kuiper Belt of objects orbiting beyond Neptune.


OuterSolar System

Ceres


The outer solar system

Beyond the Kuiper Belt of objects lies the Oort Cloud. 50,000 AU (1 ly) from the Sun it is thought to contain up to 1 trillion small icy bodies that, if

perturbed by a passing star, fall into the Solar System to be observed as comets.

never been “observed”, but inferred from comets and their orbits.

Also the heliosphere Voyager 1 passed Aug 2012 (confirmed Aug 2013)


The heliosphere

Note: non-linear distance scale


In the newsThe Guardian, September 12, 2013 by Conal Urquhart ...

Last year, scientists monitoring Voyager 1 discovered that it was no longer picking up charged particles which emanate from the sun, suggesting it had left the solar system. At the same time, there was an increase in cosmic rays coming from outside the solar system.

The scientists could not detect a change in the direction of the magnetic field lines, so assumed Voyager was still in the heliosphere, the bubble of sun-charged particles which surrounds the solar system.

The Voyager team waited for a change in magnetic field direction which they thought would signify departure from the solar system. But a solar eruption caused the space around Voyager 1 to vibrate last spring, convincing scientists that the boundary was crossed in August last year.

"Clearly we had passed through the heliopause, which is the long hypothesised boundary between the solar plasma and the interstellar plasma." said Don Gurnett, Voyager scientist.

Not everyone is convinced that the boundary has been crossed. "It's premature to judge," said Lennard Fisk, a space science professor at the University of Michigan who is concerned about the absence of a change in the magnetic field direction. "Can we wait a little while longer? Maybe this picture will clear up the farther we go."

Voyager 2 trails behind at 9.5bn miles from the sun. It may be another three years before it joins its twin on the other side. Eventually, the Voyagers will run out of nuclear fuel and will have to power down their instruments by 2025.


Where did all this come from?

Universe thought to be 13.7 billion years old. Hydrogen & helium only, all other elements from nuclear

fusion in the cores of stars

Solar system formed 4.6 billion years ago. This is the oldest radiometric date of any lump of rock

found in the solar system (meteorites).

The solar nebula hypothesis: Must explain several key observations,

a) rotation and ordered motion, b) composition and range of planets and small bodies, and c) permit exceptions such as the Moon, inclinations, etc.


p. 79


Debris disks around other stars


Disks Around Other Stars


Review Questions

Could try Ch 3, page 97-98 Questions #12, 13, 14, 15, 22, 42, 43.

Try reading the statements #25 to 34 to discuss which are reasonable and which are not.

For next week, skim Chapter 4 of the textbook.


the solar system - uvicvenn/a201/a201-week3.pdf · surrounds the solar system. the voyager team...

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