Asteroids Near Earth
Asteroid Ida (56km x 24km x 21km) and its moonlet Dactyl, photographed by the NASA probe Galileo
The phrase "Near Earth Asteroids" is most popular in the general public, but has been superceded in the scientific community by the phrase "Near Earth Objects" and given the acronym NEO, in order to distinguish between:
- asteroids -- the kinds of bodies which originated in the inner solar system, usually rocky, vs.
- comets -- which originated in the outer solar system but were captured by the inner solar system -- and may look like asteroids at first glance from a distance -- whereby their surface volatiles have boiled off long ago, so they no longer have a tail, but are probably rich in water, carbon, and other volatiles (especially nitrogen) under the surface, and may be finer and softer in texture, even powdery.
Efforts to introduce the terminology "NEO" to the general public have not resulted in broad assimilation, at least not yet, whereby many people refer to everything as "near Earth asteroids" but say "huh?" when we refer to NEOs, so for practical purposes, many of us say "NEO" when talking with professionals but only "near Earth asteroids" when talking with the general public, especially in a brief encounter with the latter.
On this website which reaches out to the general public, I will sometimes keep things simple and easy by calling things "asteroids" rather liberally for the most part, rather than be pedantic with NEO everywhere. Nevertheless, it is important to introduce people to the acronym NEO because there are significant differences. The term NEO has gotten around a lot on the internet, and even some journalists have properly complied with this.
In this categorization, "NEO" encompasses everything -- asteroids near Earth, comets, even space junk in some circles. So, asteroids near Earth are included in the group of objects called NEOs, but cometary derived NEOs in some professional circles are technically not "asteroids" in strict circles.
The vast majority of strict "asteroids" originated in the asteroid belt between Mars and Jupiter, but can be any body which originated in the inner solar system, usually rocky bodies which are usually depleted in volatiles.
Occasionally, there are the acronyms NEA for Near Earth Asteroid (vs. NEO), and MBA for Main Belt Asteroid.
The subsections of this section are all listed below.
PERMANENT.com > Asteroids, Near Earth Objects (NEO)
Additional, children pages of this current parent page:
Asteroids, Near Earth Objects (NEO) :
Overview of NEOs
NEO Location Classes
Meteorites: Samples of NEOs
Origins of Meteorites
Compositions of Meteorites
Falls vs. Finds Caveat
Reflection Spectroscopy of NEOs
Probes to Asteroids, Comets
Phobos, Deimos (Mars moons)
Giotto (Halleys Comet)
MBA Galileo flybys
Deep Space 1
Hayabusa NEA Sample Return
Rosetta Comet Lander, Orbiter
Deep Impact (Comet)
Dawn to MBA Vesta, Ceres
Fobos-Grunt (failed, Phobos)
OSIRIS-REx Asteroid Probe
Obama-Keck asteroid retrieval
Mining Asteroids and NEOs
Asteroid Lander Techniques
Impact of Earth by a NEO
Discovering New NEOs
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