Holmberg radius - A measure of the semi-major axis of a galaxy.

Stellar Wind- The ejection of gas from the surface of a star. Many different types of stars, including our Sun, have stellar winds. The stellar wind of our Sun is also known as the Solar wind. A star's stellar wind is strongest near the end of its life when it has consumed most of its fuel.

Edited July 27, 201510 yr by ACG52

Declination - the angular distance from the celestial equator.

Nakhlite - A rare class of meteorite originating on Mars & composed mainly of pyroxenes.

Einstein cross - a type of gravitational lensing resulting in 4 images of a background object.

Standard candle

 

A distance marker or measure. Typically Cepheid Variable stars or type 1A Supernovae.

Extinction- The apparent dimming of star or planet when low on the horizon due to absorption by the Earth's atmosphere.

Nereid - A moon of Neptune that has the highest eccentricity of orbit of any satellite in the solar system. Named for sea nymphs of Greek mythology.

Decretion disk-a circumstellar disk formed from gas ejected from the central star that now follows a near Keplerian orbit around it. This type of disk can be found around many Be stars.

Klemperer Rosette - a system of multiple bodies orbiting in regular patterns around a common barycenter.

Equant-The center of a planetary epicycle.

Theia - hypothetical planet in the early solar system which according to the giant impact hypothesis collided with the Earth around 4.533 billion years ago.

Apoapsis- the point in orbit farthest from the planet.

Sagan, Carl Edward - American astronomer and popularizer of science.

Dione - A moon of Saturn discovered in 1684 by Giovanni Domenico Cassini. [it wasn't named until 1847.] Dione is in a 1:2 orbital resonance with Saturn's moon Enceladus and Dione itself has two Trojan moons, Helene and Polydeuces.

Electra- one of the Pleiades

Alkaid - the proper name for the last star in the handle of the Big Dipper.

Dschubba- arabic name for δ Sco in the constellation Scorpio

Aerolite - A meteorite made up of mostly stony material.

Eclipsing Binary- A binary system where one object passes in front of the other, cutting off some or all of its light.

Yoke mounting - a particular means of mounting a telescope.

G-type star - A main sequence yellow dwarf star, the spectral type of which the sun is a member.

 

Someone end in a H, I have a good one.

Radioheliograph - A radio telescope used for studying the Sun.

Helium flash - The moment when a star begins to fuse helium. For a few brief moments the star increases its energy output 100 billion fold and produces more energy than an entire galaxy.

 

Thanks Janus.

Edited August 2, 201510 yr by Mad For Science

Harvest Moon - The full moon nearest to the autumnal equinox.