Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

One-third of the way to Pluto!

Bad AstronomyBy Phil PlaitMarch 19, 2009 10:30 PM


Sign up for our email newsletter for the latest science news

On Alan Stern's New Horizons page, he tells us that the Pluto probe has something of a milestone today: it's 1/3 of the way to Pluto in time. In other words, it's been 1155 days since launch on January 19, 2006, and New Horizons will pass Pluto on July 14, 2015, which will be 3463 days after launch. Interestingly, it passed 1/3 of the distance it will travel to Pluto some time ago! The probe was moving fastest right after launch, but has since been decelerating due to gravity from the Sun (and initially from the Earth) [Note added later: This is not quite correct; I forgot initially that the probe picked up speed at Jupiter, so in fact it's been slowing down ever since then]. It's moving more slowly now, so it takes longer to hit each distance milestone. Alan makes a remarkable comment on that page: besides the spent booster that put the probe on its course to Pluto, there are no man-made objects within a billion miles of New Horizons. Space is empty, dark, and deep in the outer solar system. But only for a few more years... and then the little probe will pass Pluto, and have plenty of things to do and see.


    3 Free Articles Left

    Want it all? Get unlimited access when you subscribe.


    Already a subscriber? Register or Log In

    Want unlimited access?

    Subscribe today and save 70%


    Already a subscriber? Register or Log In