Results 271 to 280 of about 54,891 (314)

A Search for Solar Variability

1968
The difference in brightness of two stars situated near to each other on the celestial sphere is one of the quantities that the astrophysicist can measure the most precisely. This fact stimulated the idea of searching for variability in the solar energy output by comparing the brightness of planets with that of background stars over a period of years ...
M. Jerzykiewicz, K. Serkowski
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Solar Irradiance Variability

Metrologia, 1991
Support is given for the suggestion that the mean annual value of the solar constant varies as an algebraic sum of changes in effective temperature and photospheric radius. A set of harmonic constituents covering the period 1979 to 1987 is suggested.
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Variability of the solar chromospheric network over the solar cycle

Solar Physics, 1994
From a large sample of the Kodaikanal spectroheliograms in the Call K line we have studied the variations in the intensity of the network elements over two solar cycles and have estimated their contribution to the overall variability seen in the disc-averaged K line profiles.
R. Kariyappa, K. R. Sivaraman
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The Precise Solar Shape and Its Variability

Science, 2012
Our Constant Sun The exact shape of the Sun provides information on its internal structure. Based on data obtained by the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory, Kuhn et al. (p.
J R, Kuhn, R, Bush, M, Emilio, I F, Scholl   +3 more
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Solar irradiance variability

Atmospheric Research, 1989
Since November 1978 a set of total solar irradiance (TSI) measurements from space is available, yielding a time series of more than 23 years. From measurements made by different space radiometers (HF on NIMBUS 7, ACRIM I on SMM, ACRIM II on UARS and VIRGO on SOHO) a composite record of TSI can be compiled. This leads to a reliable record of TSI with an
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Variable solar wind

Solar System Research, 2017
The solar wind in the heliosphere is a variable phenomenon on all spatial and time scales. It has been shown that there are two basic types of solar wind by the Strouhal number S = L/VT, which characterizes relative variations in the main parameters of the solar wind on the given time interval T and linear scale L for velocity V, which is never zero ...
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Variability of the solar diameter

Advances in Space Research, 1988
Abstract Although the solar diameter has been monitored for around three centuries, very little is known on its secular variations. The subject is still controversial, dealing with historical archives or with more recent observations as well. Most of the available data come from visual determinations. The precision of the measurements depends on the
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Variability of solar granulation

Advances in Space Research, 1988
Abstract The temporal variation of the mean size of granules recently discovered (Macris et al., 1983; Macris et al. 1983; Muller and Roudier, 1984) is confirmed using a new set of photographs of higher quality and homogeneity : granules are smaller at sunspot maximum.
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Solar variability and oscillations

Reviews of Geophysics, 1987
Within this decade, observations of total solar irradiance have become good enough to permit us to study directly the solar luminosity variations on a wide range of time scales, up to several years. At the same time there has been considerable improvement in understanding the classical indicators of solar activity, such as UV and visible chromospheric ...
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Solar observations in ancient China and solar variability

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1990
Abstract In this paper I review both the history of solar observations in ancient China and recent researches on solar variability. The paper consists of three parts. In the first part I describe Sun worship and the early observations of solar phenomena.
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