APOD: A Five Planet Dawn (2016 Jan 30)

[Cousin Ricky]

My definition makes at least one person happy.
Therefore the greater benefit to Humanity in general would be made by adopting my definition.

Damn!

[neufer]

But defining a planet isn't Science, it's politics.

Actually, it's a bit of both.

"Things as certain as death and taxis, can be more firmly believ’d."

• — Daniel Defoe, The Political History of the Devil, 1726.

<<Taxonomy is the practice and science of classification. The word is also used as a count noun: a taxonomy, or taxonomic scheme, is a particular classification. The word finds its roots in the Greek language τάξις, taxis (meaning 'order', 'arrangement') and νόμος, nomos ('law' or 'science'). Originally taxonomy referred only to the classifying of organisms or a particular classification of organisms. In a wider, more general sense, it may refer to a classification of things or concepts, as well as to the principles underlying such a classification. Taxonomy is different from meronomy which is dealing with the classification of parts of a whole.

Many taxonomies have a hierarchical structure, but this is not a requirement. Taxonomy uses taxonomic units, known as taxa (singular taxon).>>

"Our new Constitution is now established, and has an appearance that promises permanency; but in this world nothing can be said to be certain, except death and taxis."

• — Benjamin Franklin, in a letter to Jean-Baptiste Leroy, 1789

[ta152h0]

resisting Mr Neuendorffer is also futile

[trekman]

I dont know enough about astronomy or space to know the answer to this. Ive always been amazed at the infinitesimal number of things in the heavens. How is it that we can look at 5 specks in the sky and know exactly what planet or what star they are? Thanks.

We know what star is which because they are (to a large degree) static. They maintain the same position with respect to other stars, forming patterns that we can recognize. More technically, they maintain a position against the sky coordinate system that is fixed, just like a town or lake has a fixed latitude and longitude.

The planets are identified by position, as well, although how they move and how they appear (especially in a telescope) can also be considered.

Thank you Chris. Not being able to see all of them, all of the time makes some of us think they arent always there. At least in the same position every night.