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October 2002

Delve deeper into hot topics featured in NGM’s October Geographica and Who Knew? with help from Resources. Click on a link, pick up a periodical, browse through a book, and explore!
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Science can get a reputation as narrow-minded just because it rejects things like Bigfoot and the claims that people can bend spoons with mind beams. But science has introduced us to its own magnificently weird phenomena: dinosaurs, an expanding universe, and so on. Now comes a report of a possible new member of the cosmic bestiary: the quark star.

The Chandra x-ray telescope satellite took a look at two objects euphoniously named RX J1856.5-3754 and 3C58. These were believed to be neutron stars—stars that exploded as supernovas, then collapsed under their own gravity, becoming so crunched that even their atoms imploded, leaving only an unimaginably dense knot of neutrons. A teaspoon of neutron star stuff, says NASA, weighs as much as all the cars, trucks, and buses on Earth.

Problem was, these stars didn’t fit the neutron star model. They were too dense! Some astronomers think that Chandra may be peering at an entirely new form of matter. RX J, one team suggests, could be a quark star.

Quark stars are thought to be made of degenerate quark matter, which is not meant as an insult. The neutrons in these stars would have dissolved, leaving only a disorderly scrum of particles called up, down, and strange quarks.

Or maybe the model for neutron stars is wrong. While astronomers and theorists sort it out, we might ponder a bigger question: What else is out there? How complete is our census of the heavens?

Obviously we can’t count the things we don’t know. But we can speculate. Astronomer Martin Harwit has come up with his own statistical estimation of the cosmic unknown. He makes the analogy to baseball cards. You start the season collecting cards at random. Over time you encounter duplicates. The more cards you have, the more likely your next card will be a duplicate. By the time you’ve collected a hundred or so, you can use the rate of duplication to estimate the total number of cards.

Now shift to astronomy. Harwit some years ago listed all the phenomena we’ve already detected. Then he looked for what he calls duplicate discoveries. For example, pulsars—a type of neutron star detected in the 1960s with radio telescopes—would likely also have been discovered with more recent x-ray telescopes like Chandra.

His conclusion? “We probably have uncovered something on the order of a third to half of the major phenomena.” The easy discoveries are behind us. Those ahead will be increasingly elusive. Says Harwit, “It might take us many more centuries to come to the end of our search.”

By which time we’ll have motels orbiting quark stars.

— Joel Achenbach
Washington Post staff writer

Web Links Rough Draft
Writer Joel Achenbach’s column is gaining a cult following. It takes a sometimes humorous, sometimes eye-squinting, but always intelligent look at today’s headlines, personal interests, and the little life-annoyances we all live with.

America’s River

Take a look at Joel’s recent piece for the Washington Post on “America’s River,” the Potomac, and its remarkable history. Science
More science news from Joel’s other home, the Washington Post.

Chandra X-Ray Observatory Center
Learn more about x-ray astronomy and see images of RX J1856.5-3754 and 3C58, the stars featured in this month’s column.

Imagine the Universe!
NASA’s Laboratory for High Energy Astrophysics introduces you to the electromagnetic spectrum, gamma-ray astronomy, white dwarfs, neutron stars, black holes, and other high-energy phenomena in the universe.

Human Physiology in Space
The National Space Biomedical Research Institute’s easy-to-read textbook on what happens to the human body in space.

Free World Map

Achenbach, Joel. “Power of Light,” National Geographic (October 2001), 2-31.

Harwit, Martin. Cosmic Discovery: The Search, Scope and Heritage of Astronomy. Basic Books, Inc., 1981.

Lidsey, James. The Bigger Bang. Cambridge University Press, 2000.

Long, Michael. “Surviving in Space,” National Geographic (January 2001), 6-29.

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