University Washington EPSC 171A, Spring 2008 January 15, 2008
The textbook (required) is Astronomy Today, by Chaisson & McMillan, Sixth Edition. We use only "Volume 1" of this text (Chapters 1-16 plus 28). Our version comes with the "planetarium" program SkyChart III (access details TBA). There is a companion website www.aw-bc.com/chaisson www.aw-bc.com/chaisson which provides an ebook, images and animations, selfhelp facilities, etc.
Exams and Exercises There will be two in-class mid-term examinations (each accounting for 16% of the course grade), a final examination (accounting for 32%) and various student "exercises" (cumulatively accounting for 36% of the grade). The "exercises" will include three internet exploration (e.g. finding planetary data and images) exercises and one focused on use of the Skychart III program, and a term paper (approx 3000 words). In addition there will be three "out of classroom" exercises: Attendance of a McDonnell Center public lecture (maybe);A telescope/planetarium experience (details TBA); An evening movie. Each of these three is to be followed by a 500-word report on the experience. Staff Instructor: TAs: Frank A. Podosek, EPSC 327, 5-7367, [e-mail] Andrew Foreman, [e-mail] Sean O'Donnell, [e-mail] Colin Wilson, [e-mail] Website: TBA Schedule
Syllabus
This shows the night sky above St. Louis, just after sunset on January 15, 2008. The stars move across the sky, rising and setting. But they keep fixed relative positions. The motion can be described as rotation about a fixed point in the sky;
The motion of the stars is consistent with their being attached to a rigid sphere the celestial sphere which rotates around the Earth once every 24 hours. This was pretty much Western Civilization's view of the heavens for some 2000 years.
Against the backdrop of the "fixed stars" (the celestial sphere) there are two kinds of transitory (one-time) phenomena, which we now call comets (visible for days to months) and meteors (a few seconds or less). The ancients considered these to be atmospheric rather than celestial phenomena. (They were right about meteors, not about comets.)
But some objects planets (= "wanderers") move across the sky, relative to the fixed stars, in more or less regular fashion. There are seven such objects (visible to the naked eye). Two of them the Sun and the Moon are clearly extended physical objects of great importance to human culture. The other five Mercury, Venus, Mars, Jupiter and Saturn are just points of light (to the naked eye). Nobody knew what they were, although this seemed of lesser importance than explaining their motion.
Many people had this picture of the solar system for a long time.
A view outside the cosmos.
These days, the "solar system" is the Sun plus a few objects left over from the formation of the Sun.
The main factors involved in this different vision were changes in the philosophical approach to cosmogony, understanding of the laws of dynamics, continuing development of telescopes and spectroscopy and, in the last generation, spacecraft exploration.
The planets are pretty spread out.
The central feature of the solar system is the Sun.
The Earth is a planet, one of the bodies left over from the birth of the Sun.
Fortunately, the Earth turns out to be an extremely nice place to live.
The Earth is a pretty active planet.
Considering how close it is, and that it's made of similar materials, the Moon is a rather different place.
Mercury is about the same size as the Moon, and looks like it.
Venus, some in respects the Earth's "twin", has an atmosphere about a hundred times thicker than the Earth's and a surface temperature near the melting point of lead.
The surface of Venus is a lot like the classical picture of Hell.
Although it's a lot smaller, Mars in many respects is the planet most similar to Earth.
Mars is also the planet thought to have the best chance for present or past extraterrestrial life.
Mercury, Venus, Earth, the Moon, Mars and the asteroids are collectively called the terrestrial planets. They are made of rock and metal, with maybe a smidge of gases.
Eros, an asteroid.
Jupiter, Saturn, Uranus and Neptune are collectively called the Jovian planets. In contrast to the terrestrial planets, the Jovian planets are made of gases, not solids. The gases are mostly hydrogen and helium, i.e. their compositions are like the Sun's. They tend to have dynamic and rather complex atmospheric circulation patterns.
The Jovian planets all have extensive families of satellites, like little solar systems.
The satellites are interesting in their own right. Io, for example, is the most active planetary body in the solar system.
Europa is the second-most popular (after Mars) prospective home for extraterrestrial life, because it is thought to have an ocean of liquid water under a surface of ice.
Saturn's moon Enceladus apparently has liquid water only a few tens of meters below the surface, liquid that sometimes erupts to the surface.
Iapetus, a moon of Saturn, has an equatorial ridge 12 miles high.
All the Jovian planets have rings, too, but certainly Saturn's are the best known and the most spectacular.
Pluto (shown with its satellite Charon) is not a Jovian planet. Indeed, there is currently somewhat of a controversy about whether it should be called a planet at all. Like most of the Jovian planet satellites, it is thought to be made of ice and rock.
Comets are small icy bodies that usually reside in the outer reaches of the solar system. When they visit the inner solar system they can put on quite a show.
Sometimes we get quite a show on Earth too, e.g. the Park Forest (near Chicago) meteorite of March 26, 2003.
Two rovers, Spirit and Opportunity, la...