Ask Ethan #43: Decaying Gravitational Orbits

If you thought “planets move about the sun in ellipses,” wait until you read this.

Ethan Siegel
Jun 27, 2014 · 7 min read
Image for post
Image for post
Image credit: Petr Scheirich, 2005, via http://sajri.astronomy.cz/asteroidgroups/groups.htm.
Image for post
Image for post
Image credit: Wikimedia Commons user Dennis Nilsson, via c.c.-by-3.0.
Image for post
Image for post
Image credit: © Pittsburgh Supercomputing Center, Carnegie Mellon University, University of Pittsburgh, via http://www.psc.edu/science/2006/blackhole/.
Image for post
Image for post
Image credit: Chaisson, Eric; McMillan, Steve, ASTRONOMY, 2004. You can ignore the Asteroid belt and Pluto for our purposes.
Image for post
Image for post
Image credit: NASA’s Solar and Heliospheric Observatory, joint NASA / ESA mission, via http://sohowww.nascom.nasa.gov/.
Image for post
Image for post
Image credit: original source Michael Richmond; modifications by me.
Image for post
Image for post
Image credit: Joe Bergeron of Sky & Telescope magazine.
Image for post
Image for post
Images credit: The Parent Company (L), via http://www.parentcompany.com/creation_explanation/cx6a.htm; Institute of Physics (R), via http://tap.iop.org/atoms/duality/507/page_47057.html.
Image for post
Image for post
Image credit: Tom Murphy of UC San Diego, via http://physics.ucsd.edu/~tmurphy/apollo/basics.html.
Image for post
Image for post
Image credit: NASA (L), Max Planck Institute for Radio Astronomy / Michael Kramer, viahttp://www.mpg.de/7644757/W002_Physics-Astronomy_048-055.pdf.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch

Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore

Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store