Astronomers Measured Mass of Largest Dwarf Planet

June 18, 2007
Astronomers Measure Mass of Largest Dwarf Planet

Aptly named after the Greek goddess of conflict, the icy dwarf planet, Eris, has rattled the general model of our solar system. The object was discovered by astronomer Mike Brown of Caltech in the outer reaches of the Kuiper belt in 2005.

Its detection provoked debate about Pluto’s classification as a planet. Eris is slightly larger than Pluto.

So if Pluto qualified as a full-fledged planet, then Eris certainly should too. Astronomers attending the International Astronomical Union meeting in 2006 worked to settle this dilemma. In the end, we lost a planet rather than gaining one. Pluto was demoted and reclassified as a dwarf planet along with Eris and the asteroid Ceres, the most massive member of the asteroid belt.

Adding insult to injury for the former ninth planet, Brown has now determined that Eris is also more massive than Pluto. This new detail was determined by observations of Eris’ tiny moon Dysnomia. The Hubble Space Telescope and Keck Observatory took images of the moon’s movement, from which Brown precisely calculated Eris to be 27 percent more massive than Pluto. In fact, if you scooped up all the asteroids in the asteroid belt they would fit inside Eris, with a lot of room to spare.

Currently, Eris is more than three times farther from the Sun than Pluto. It is so cold out there that the dwarf planet’s atmosphere has frozen onto the surface as a frosty glaze. The coating gleams brightly, reflecting as much sunlight as fresh fallen snow. The path Eris takes around the Sun is shaped like an oval rather than a circle. In about 290 years, Eris will move close enough to the Sun to partially thaw. Its icy veneer will melt away revealing a rocky, speckled landscape similar to Pluto’s.

Source: NASA/Space Telescope Science Institute, Baltimore, by Ray Villard

Explore further: Outer solar system experts find 'far out there' dwarf planet

Related Stories

Outer solar system experts find 'far out there' dwarf planet

December 17, 2018

A team of astronomers has discovered the most-distant body ever observed in our Solar System. It is the first known Solar System object that has been detected at a distance that is more than 100 times farther than Earth is ...

Team makes breakthroughs studying Pluto orbiter mission

October 24, 2018

A Southwest Research Institute team using internal research funds has made several discoveries that expand the range and value of a future Pluto orbiter mission. The breakthroughs define a fuel-saving orbital tour and demonstrate ...

What is the newest planet?

July 7, 2015

With astronomers discovering new planets and other celestial objects all the time, you may be wondering what the newest planet to be discovered is. Well, that depends on your frame of reference. If we are talking about our ...

Eris' moon Dysnomia

July 29, 2015

Ask a person what Dysnomia refers to, and they might venture that it's a medical condition. In truth, they would be correct. But in addition to being a condition that affects the memory (where people have a hard time remembering ...

Recommended for you

Saturn hasn't always had rings

January 17, 2019

One of the last acts of NASA's Cassini spacecraft before its death plunge into Saturn's hydrogen and helium atmosphere was to coast between the planet and its rings and let them tug it around, essentially acting as a gravity ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.