Home Gallery Introduction Prints Entire Gallery Binary Star Systems Extrasolar Planets Galaxies The Solar System Stars Glossary
 


Glossary

This page is meant to make it easier for you to understand the content of this web site. The glossary contains both astronomical and art terms.


P

Parallax: The shift a star appears to make when viewed from two different locations. The closer the object the larger shift. This is a method which has a lesser accuracy the further away the object is.

Parsec: A distance scale, 3.26 light years, or about 30 trillion kilometres.

Periastron: A point in an orbit in which the object is closest to its' main star.

Perigee: The point in the moon's orbit around earth on which it is closest.

Perihelion: The point in an object's orbit around the sun on which it is closest.

Period-Luminosity Relation: A relationship between the pulsation period of a variable star and its luminosity. Generally the more luminous the star the longer the pulsation period. The relationship permits distances to be measured.

Pesek, Ludek (1919-1999): Illustrator and fine artist. His work became known to the american audiance through the National Geographic Magazine. More. Ludek Pesek gallery.

Photon: A photon is a light wave/particle, whether be it is a radio wave or a gamma ray. Link: Photons and radiation.

Planet: A large object which does not produce its own energy and does orbit a star. The difference between a planet or an asteroid is sometimes vague. How large does an object have to be, to be called a planet?

Planetary nebula: A kind of a nebula that is created when a star throws off a huge amounts of gas. The sun is believed to create one when it will near the end of its life. Nebulae give birth to new stars. Link: Planetary nebulae.

Population I stars: Relatively young stars, containing a larger fraction of metals, found mainly in the disk of the Galaxy.

Population II stars: Relatively old stars, containing a smaller fraction of metals, found mainly in the halo of the Galaxy and in Globular Clusters.

Proton: The second part of an atomic nuclei. It is positively electrically charged. The other part is a neutron, which is neutral in charge.

Proton-proton chain: The fusion reaction of four protons which become a helium atum with two protons and two neutrons, and a very energetic light wave, a photon. A neutrino is also produced in this chain. Link: Fusion processes and radiation.

Protoplanet: This is an early stage of a planet's formation. It is a clump of material which may gather more material to make a planet.

Protostar: A clump of gas which may become a star if it has enough mass. When the gravitational pressure which points inwards is balanced by an equal internal gas pressure, pointing in the opposite direction is achieved a star is born. Not all protostars become real stars.

Pulsar: A rotating magnetized neutron star that produces regular pulses of radiation when observed from a distance. A pulse is produced every time the rotation brings the magnetic pole region of the neutron star into view. In this way the pulsar acts much as a light house does, sweeping a beam of radiation through space.







 




A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



< O Q >













 
 

All content Copyright , 2005- by Fahad Sulehria, unless stated otherwise.
Free image use: Frequently Asked Questions.