Jump to content
Sign in to follow this  
  • entries
  • comments
  • views

Orbital Decay and You



(You, of course, indicating its impact on the Earth and not necessarily you on a personal level.)

By essentially sapping energy from an orbital system, gravitational radiation makes orbits more circular and continuously decreases their radii. Overall angular momentum decreases, as this too is essentially stolen by radiation. The decrease in the radius of orbit is given by the following equation:blogentry-1405-0-94046100-1421976462_thu

Substitution of the Earth's and Sun's masses for m1 and m2 tells us that the rate of our orbit with the Sun is decreasing by the second: 1.1 * 10^-20 meters per second, to be exact. Not to freak you out or anything, but we're getting closer and closer to the Sun as you read this. In exactly 365 days (that's a year in math terms), we will be MUCH closer to the Sun than we are now. About 1/300 of the diameter of a hydrogen atom. Now that's a bafflingly huge number, but I'm sure we have a few years left under our belt before we collapse into the Sun and die fiery deaths.

This equation can tell us the lifetime of an orbit as well, before this collapsing occurs. However, since the rate of change depends on the radius and not time, integration of the equation is necessary. So the lifetime of an orbital radius is brought to you by this guy here: blogentry-1405-0-24812000-1421976851_thu

Again, substituting in the Earth's and Sun's masses, we find our orbit to be about 1.09 * 10^23 years. Seems pretty massive, especially considering this is 10^13 times larger than the age of the Universe itself.

Well, I hope you learned something, and I'll see you next quarter. :)


Recommended Comments

There are no comments to display.

Add a comment...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Terms of Use

The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.

Copyright Notice

APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to info@aplusphysics.com. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.

  • Create New...