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Å

Å   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

Symbol for *angstrom.

A-OK

A-OK   Quick reference

A Dictionary of Space Exploration (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

‘Very OK’ or ‘Great’. John ‘Shorty’ Powers, NASA's public-relations officer, introduced the term by misquoting astronaut Alan *Shepard during the first sub-orbital flight in ...

A-type asteroid

A-type asteroid   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

A rare type of asteroid that has both a moderately high albedo (0.13–0.35) and an extremely reddish spectrum at wavelengths shorter than 0.7 ...

A-type rocket

A-type rocket   Quick reference

A Dictionary of Space Exploration (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

A name used in the West for a series of Soviet rocket boosters. The A-1 launched *Sputnik and the cosmonaut ...

AAO

AAO   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

Abbr. for *Australian Astronomical Observatory.

AAS

AAS   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

Abbr. for *American Astronomical Society.

AAT

AAT   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

Abbr. for *Anglo-Australian Telescope.

AAVSO

AAVSO   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

Abbr. for *American Association of Variable Star Observers.

A band

A band   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
A broad *Fraunhofer line in the Sun’s spectrum at around 759 nm, due to absorption by oxygen in the Earth’s atmosphere. Because the oxygen is in molecular form, the A band is actually a ... More
Abell clusters

Abell clusters   Reference library

The Oxford Companion to Cosmology

Reference type:
Subject Reference
Current Version:
2008

George Abell is best remembered for his catalogue of clusters of galaxies, a result of his PhD work at the

Abell Catalogue

Abell Catalogue   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

A catalogue of 2712 rich clusters of galaxies published in 1958 by the American astronomer George Ogden Abell (1927–83...

Abell cluster

Abell cluster   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
A cluster of galaxies listed in the *Abell Catalogue. To appear in the catalogue, a cluster must satisfy selection criteria which include containing more than 50 galaxies and having a ... More
Abell radius

Abell radius   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

A radius of about 2 megaparsecs within which at least 50 galaxies of a particular range of brightness must be found if the cluster is to qualify as an ...

aberration, optical

aberration, optical   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

An imperfection or error in the image produced by a lens, mirror, or optical system. There are six types of aberration: ...

aberration of starlight

aberration of starlight   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
Subject:
Science and technology, Astronomy and Cosmology
Length:
152 words
Illustration(s):
1
The small apparent difference between the observed direction of a star and its true direction (see diagram). It is due to the combined effect of the observer’s motion across the path of ... More
ablation

ablation   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
The wearing away of the outer layers of a body by melting, erosion, vaporization, or some other process due to aerodynamic effects as the body moves at high speed through a planetary ... More
ablation age

ablation age   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
The period of time since the outer glassy layers of a tektite solidified following ablation during its re-entry into the Earth’s atmosphere. The ablation ages of known tektites vary from ... More
ablation shield

ablation shield   Quick reference

A Dictionary of Space Exploration (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
The heat shield on a spacecraft to protect it during re-entry. The intense heat generated by friction during the high-speed entry of the craft into the Earth's atmosphere burns away ... More
abort

abort   Quick reference

A Dictionary of Space Exploration (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
A premature end of a space flight due to danger to the crew, the mission, or the environment, such as an accident or systems failure. This can occur during launch or during a mission. The ... More
abort sensing and implementation system

abort sensing and implementation system   Quick reference

A Dictionary of Space Exploration (3 ed.)

Reference type:
Subject Reference
Current Version:
2018
The automatic detection system added to the *Atlas rocket in 1959 to create near-perfect reliability for crewed space flights. ASIS could sense and signal an impending catastrophic failure ... More

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