2007 GSA Denver Annual Meeting (2831 October 2007)
Paper No. 218-10
Presentation Time: 4:00 PM-4:15 PM


FIELDS, Brian, Astronomy, University of Illinois, 1002 W. Green St, Urbana, IL 61801, bdfields@uiuc.edu

The lifespans of the most massive stars are a symphony of the fundamental forces, culminating in a spectacular and violent supernova explosion. While these events are awesome to observe, they can take a more sinister shade when they occur closer to home, because an explosion inside a certain "minimum safe distance" would pose a grave threat to life on Earth. We will discuss these cosmic insults to life, and ways to determine whether a supernova occurred nearby over the course of the Earth's existence. We will then present recent evidence that a star exploded near the Earth about 3 million years ago. Radioactive iron-60 atoms have been found in deep-ocean ferromanganese crusts, and are likely to be debris from this explosion. Recent data confirm this radioactive signal, and for the first time allow sea sediments to be used as a telescope, probing the nuclear reactions that power exploding stars. Furthermore, an explosion so close to Earth was probably a "near-miss," which emitted intense and possibly harmful radiation. The resulting environmental damage may even have led to extinction of species which were the most vulnerable to this radiation.

2007 GSA Denver Annual Meeting (2831 October 2007)
General Information for this Meeting
Session No. 218
Planetary Geology: Potpourri
Colorado Convention Center: 605/607
1:30 PM-5:30 PM, Wednesday, 31 October 2007

Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 591

© Copyright 2007 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.