Read Seeds: Section 5.1

Figure 1: 49KB Text Credit: NASA/STScI/Jeff Hester and Paul Scowen (Arizona State University) Figure 2: 78 KB Text Credit: C.R. O'Dell/Rice Univ., NASA Figure 3: 80KB Text Credit: Mark McCaughrean (Max-Planck-Institute for Astronomy), C. Robert O'Dell (Rice University), and NASA Figure 4: 79KB Text Credit: C.R. O'Dell/Rice Univ., NASA

How does one go about developing a theory of the origin of the Earth and the solar system to which it belongs? First, we can observe stars and planetary systems forming today. Figure 1 is one of the most dramatic pictures provided by the Hubble Space Telescope. The pillar-like structures located in the Eagle Nebula (M16) are a dramatic example of active star formation going on today. Long known to be a region of active star formation, the Orion nebula (figure 2), under the penetrating eye of the Hubble Space Telescope (Mpg video - 650 KB) (Text), has provided a wealth of information about star formation and, potentially, the evolution of planetary systems. Of particular interest, is the discovery of protoplanetary disks ("proplyds"). These protoplanetary disks are dark disks of dust and gas which have been found around new, hot stars in the Orion nebula (figures 3 and 4). It has long been theorized that planetary systems form out of such disks of dust and gas which has been left behind as a remnant of the star formation process. Thus the Orion nebula and the "proplyds" provide a means of testing and refining our current theories of solar system formation. A second approach taken by astronomers is to develop theories of solar system formation that is consistent with the properties of our solar system as we observe them today. So let us examine those properties..... Complete these Self-check Questions: Refer to the text link in figure 1. To what does the term "EGGS" refer. What is their significance? (ans.) Refer to the text link in figure 1. What are the two primary constituent materials which comprise the globules in the Eagle nebula ? (ans.) Refer to the text link in figure 2. What is the significance is the Orion nebula? (ans.) Refer to the text link in figure 3. What is the range in the masses of the stars forming in the Orion nebula? (ans.) Refer to the text link in figure 3. What is the composition of "proplyds". What is their approximate size? How do astronomers explain the different shapes observed for proplyds? (ans.) Homework Questions: (To submit your answers to the homework questions, first copy the questions from this page and paste them into the homework form. Insert your answers below the questions. Fill in the remaining form elements and submit. Your homework will be e-mailed to me. I will return your graded homework to you in the private e-mail of the comm center). Refer to the figures on this page and the related text links associated with them to answer questions 4 through 6. What is the distance of the Orion nebula in light years? How many parsecs is that? What percentage of the Orion nebula is dust? gas? (2 points) What is the range in the masses of the stars forming in the Orion nebula? What is the range in the diameters of the protoplanetary disks detected in the Orion nebula. (2 points) What are "proplyds". Of what significance are they? (1 point) View These Optional Related Web Sites: Visiting these sites are optional, not required. Astronomy Picture of the Day: Planets Around Normal Stars Astronomy Picture of the Day: Lalande 21185: The Nearest Planetary System? Discovery of a Planetary Orbit Around the Nearby Star 51Pegasi Searching for Extrasolar Planets Possible planet orbiting Beta Pictoris A Parade of New Planets The Nine Planets: An Overview of the Solar System