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Melrose, city, United States

(Encyclopedia)Melrose, city (1990 pop. 28,150), Middlesex co., E Mass., a suburb of Boston; settled c.1629, set off from Malden and inc. 1850. It is chiefly residential. The opera star Geraldine Farrar was born in ...

twilight

(Encyclopedia)twilight, period between sunset and total darkness or between total darkness and sunrise. Total darkness does not occur immediately when the sun sinks below the horizon because light from the sun that...

Bessel, Friedrich Wilhelm

(Encyclopedia)Bessel, Friedrich Wilhelm frēdˈrĭkh vĭlˈhĕlm bĕsˈəl [key], 1784–1846, German astronomer and mathematician. He became (1810) director of the new observatory at Königsberg and professor of a...

southern tick-associated rash illness

(Encyclopedia)southern tick-associated rash illness (STARI) or Masters disease, illness characterized by a Lyme disease–like rash that is associated with bite from the Lone Star tick (Amblyomma americanum) rather...

Cepheid variables

(Encyclopedia)Cepheid variables sēˈfēĭd [key], class of variable stars that brighten and dim in an extremely regular fashion. The periods of the fluctuations (the time to complete one cycle from bright to dim a...

crescent

(Encyclopedia)crescent, emblematic representation of the quarter moon. The crescent and star, ancient Byzantine symbols that became the emblems of Constantinople, were also assumed as the standard of the Ottoman Tu...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...

Arcturus

(Encyclopedia)Arcturus ärkto͝orˈəs [key], brightest star in the constellation Boötes and 4th-brightest star in the entire sky; Bayer designation Alpha Boötis; 1992 position R.A. 14h15.3m, Dec. +19°13′. An ...

planet

(Encyclopedia)planet [Gr.,=wanderer], a large nonluminous body of rock, gas, or ice that orbits the sun or another star, has a rounded shape due to gravity, and has cleared its orbit of smaller objects. The term, o...

observatory

(Encyclopedia)observatory, scientific facility especially equipped to detect and record naturally occurring scientific phenomena. Although geological and meteorological observatories exist, the term is generally ap...