Have you ever wondered why the planets in our solar system
are the way they are? For example, why are the inner planets (Mercury, Venus,
Earth and Mars) rocky and the outer planets (Jupiter, Saturn, Uranus and
Neptune) gaseous? How did the planets get to their current locations? When did
the planets form? What are the planets made of? All these questions are topics
that planetary geologists spend their careers researching. But how?
 |
| Schematic of our solar system with Mercury, Venus, Mars and Earth in the inner solar system, respectively. The rocky planets are followed by the asteroid belt that separates them from the gaseous planets: Jupiter, Saturn, Uranus and Neptune. Beyond Neptune is the Kuiper belt with more asteroids. |
We use these things called meteorites. Meteorites are small
(but sometimes really big) objects that formed in space, traveled all the way
to Earth, and survived the descent through Earth’s atmosphere to land
(potentially) in our back yards. Meteorites come in all shapes and sizes. Most
importantly, they are made up of a wide range of compositions. One type of meteorite useful to planetary geologists is iron meteorites, which are made up of 100% iron and nickel.
 |
| Photo of an iron meteorite. |
Iron meteorites are particularly useful because they are believed to be some of the very first objects that
formed in our solar system (way before the Earth) as far back as 4.5 billion
years ago. We can study many things from them to learn about where they came
from and when they formed. We use certain elements like tungsten (W) and molybdenum
(Mo), which are very common mining products in the United States. The abundances of certain forms of these elements can tell us about an iron meteorites’ age and genetic heritage. An iron
meteorites’ genetic heritage is much like our own genetic heritage. You, your
brother and your sister are all descendants of one common ancestor that descended from a certain location. Many
different iron meteorites can descend from their own common ancestor, a small planet and come from a certain location.
 |
| Although almost all elements on the periodic table are found in our solar system, only several are beneficial when it comes to iron meteorites. We use select elements to help characterize iron meteorites in order to gain insight into the processes that occurred early in our solar system’s history. |
Many planetary geologists think that all meteorites fall into two groups and come from two different locations. Think of these two groups as two families that came from North America and Europe. These families were never able to travel to one another because the oceans kept them apart. As a result, the families never met one another and were never able to mix their genes. This is what planetary geologists believed happened with iron meteorites. One group formed inside Jupiter's orbit (where the Earth is) and the other group formed outside Jupiter's orbit. Jupiter never allowed the meteorites to mix, causing them to be genetically different from one another. Because of this, we can use abundances of certain elements within iron meteorites to tell us about the unique processes that occurred during their formation.
This is a good start, especially with the meteorite genealogy illustration, but you will lose you general audience quickly with the mention of isotopes and the presentation of the periodic table. It may be enough to talk about W and Mo (reminding the reader how these elements are important to society) and how the abundance of certain forms of these elements can tell us about the age of the meteorite, or about processes during the formation of the solar system.
ReplyDeleteFocusing more on the elements to get people engaged and then breezing past the idea of isotopes may be more helpful! But you set this up really well!
ReplyDeleteI had a hard time following this post all the way through. The second paragraph, where you describe the different types of meteorites, was very clear but the figure complicated what you took so much time to set up. It doesn't seem like knowing the secondary groups is necessary for this explanation of meteorites. I'm also unclear about the Skittles and M&M's metaphor -- did you use them specifically because they look the same? What does it mean for them to be "distinct" from one another when each candy is a discrete unit? Do the flavors mix, or would there be M&M's in the Skittles bowl?
ReplyDeleteI think the beginning of your paper was very straightforward and grabbed me as a reader. As I kept reading I got lost in a lot of the terminology and I think some of the explanations need to be more simplified
ReplyDeleteI really like the opening paragraphs of this post, but you lost me at the isotope analysis. I would recommend finding metaphors for describing those, or think of a way to condense the material in a less jargon-heavy way. Your description about genetic heritage is really good--maybe flesh it out a little and compare individual traits to the isotopic information instead of directly referencing them?
ReplyDeleteI liked your genetic heritage analogy. You could also say "family tree," in case your audience does not understand what "genetic heritage" means. I also liked your Skittles and M&Ms analogy. Maybe include an image of the two groups of iron meteorites. If you wanted to cut out some information, I do not think the explanation of different types of meteorites is necessary (the second paragraph).
ReplyDelete