Saturday Scenes

Thu 24 March 2011

Calling Occupants of Interplanetary Craft

Filed under: #satscene —— Sylvia @ 17:39

On the 19th of March in 1915, Wikipedia says that “Pluto is photographed for the first time but is not recognized as a planet.”

This statement is 100% true although somewhat confusing based on tiny detail that Pluto still isn’t recognised as a planet. Or should I say, any longer?

Astronomers were searching for a Planet X beyond Neptune from 1906. In 1915 two photographic plates were taken which included faint images of Pluto but no one noticed them in the night sky. It wasn’t until 15 years later that Pluto was spotted on a plate by a young astronomer.

As from 1930, Pluto held the happy status of planet until astronomers began to understand that it was a part of the Kuiper belt. The Kuiper belt is a collection of icy objects, similar to the asteroid belt but much larger, located at the outer edges of our solar system.

Ceres lost its planet status in 1802 when it was discovered that it was one of many objects in what we now know as the asteroid belt. Ceres instead was designated the first asteroid.

When a further large object was discovered beyond the Kuiper belt, Eris, things came to a head. It was heralded by many as the tenth planet and others argued that neither Eris nor Pluto deserved the title. The need for a clear definition of “planet” became a priority.

In 2006, the International Astronomical Union agreed upon the following definition:
IAU 2006 General Assembly: Result of the IAU Resolution votes

The IAU members gathered at the 2006 General Assembly agreed that a “planet” is defined as a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
(c) has cleared the neighbourhood around its orbit.

As a result, it was clear that Ceres, Eris and Pluto were not planets, because they did not qualify on point c. All three, however, were given the consolation prize of being the first members of the “dwarf planet” category and allowed to keep their names.

Meanwhile, on the 19th of March in 2011, many photographers looked to the skies for a less controversial reason: to see the super moon which was glowing beautifully in the sky that night. And some of those photographs are included on this fantastic set of Saturday Scenes from around the world:

These shining images were brought to you by the following super stars:

It’s easy to take part!

1) Take a photo on a Saturday and upload it to a site like Flickr or Fotonomy
2) Twitter the url for your photograph to @SatScenes
3) Watch for the next post on Saturday Scenes to see a fun set of all the photographs together.

I’m looking forward to seeing your scenes next Saturday!

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