Eak

V The symbol for visual > magnitude. UBV photometry. vacuum tower telescope A design of telescope for observations of the Sun. One at the Sacramento Peak Observatory is typical. In that instrument, sunlight enters the tower 41 m (135 feet) above the ground. A further 67 m (220 feet) of the telescope lie below ground. The entire optical path is virtually air-free, to avoid distortion of the solar image that hot air would cause. In the observing room, an image of the Sun 51 cm (20 inches) in...

P

PA (p.a.) Abbreviation for > position angle. Paaliaq A small outer moon of Saturn, in a very elliptical orbit. It was discovered in 2000 and is about 19 km (12 miles) across. 2 Pallas A large asteroid discovered by Heinrich W. M. Olbers in 1802. With a diameter of 533 km (331 miles), it is the second largest asteroid. It is of the carbonaceous type, similar to the largest asteroid, > Ceres. Its orbit is at the unusually steep inclination of 35 to the plane of the solar system. Pallene A...

Radio Astronomy Club

RA Abbreviation for > right ascension. radar astronomy The use of radar for astronomy. Radar can be used to detect > meteor showers, to measure distances to bodies in the solar system and determine their size and shape, and to map the surfaces of planets and moons. Radar signals transmitted by the 305-m (1000-foot) radio telescope at > Arecibo Observatory have been used to map Venus and to characterize the size, shape and structure of > asteroids. The > Magellan spacecraft, placed in...

Jpl

The US > National Aeronautics and Space Administration (NASA) and of other agencies. It is the principal center in the USA for the development and operation of interplanetary spacecraft. Jewel Box (NGC 4755) An open star cluster in the constellation Crux. Its brightest member is a sixth-magnitude, blue, supergiant star, Kappa Crucis. It includes several blue and red supergiants and its appearance in a small telescope is impressive. The contrasting colors of the stars is said to be why John...