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Soon after he proposed three classic observational tests for the general theory of relativity, Einstein realised that a consistent description of the universe as a whole provided another important challenge for the theory. In this essay, we…
The first observations with the 25 cm telescope of the Shumen Astronomical Observatory led to the following conclusions: (a) Intra-night observations of variable stars with an amplitude larger than 0.1 mag are possible down to 14 mag with…
A brief review is given of some recent positive developments regarding the reception of archaeoastronomy by the archaeological institutions in Italy. Discussions and problems that are currently going on in this field are also mentioned,…
Galileo Galilei was a skilled writer and explored several genres, from the well-known scientific writings (often in the form of dialogs) to theater and poetry. His last published poem, "Mostro son io" (A Monster am I), is a riddle written…
A hundred years ago, two British expeditions measured the deflection of starlight by the sun's gravitational field, confirming the prediction made by Einstein's General theory of Relativity. One hundred years later many physicists around…
This article presents a brief review of some historical and philosophical aspects of Einstein's 1917 paper 'Cosmological Considerations in the General Theory of Relativity', a landmark work that denoted the starting point of modern…
The location of a repeat plume detected at Europa is found to be coincident with the strongest ionosphere detection made by Galileo radio occultation in 1997.
Astronomical interest within the current Colombian territory has its roots in the Botanical Expedition of the New Kingdom of Granada (1783-1813), which stimulated the creation of an astronomical observatory in 1803, the first one…
Astronomical observations were used as a marker for time and the Calendar from ancient times. A more subtle calibration of epochs is thrown up by an observation of the position of the solstices and equinoxes, because these points shift in…
Goldbach's comet is the plot of the Goldbach function g(n), in the interval [3, N], with a large positive integer N. The function g(n) counts the number of different ways in which 2n can be expressed as the sum of two odd primes. An…
Deflection of light by gravity was predicted by General Relativity and observationaly confirmed in 1919. In the following decades various aspects of the gravitational lens effect were explored theoretically, among them the possibility of…
This is a pedagogical overview of neutrino physics from the invention of neutrino by Pauli in 1930 to the precise measurement of neutrino mass and mixing parameters via neutrino oscillation experiments in recent years. I have tried to pitch…
Some verses of Dante Alighieri suggest his astrological sign and his probable date of birth. This leads us to reflect on the different methods, increasingly divergent, with which sciences as opposed to beliefs approach reality.
Gravitational lensing - the deflection of light rays by gravitating matter - has become a major tool in the armoury of the modern cosmologist. Proposed nearly a hundred years ago as a key feature of Einstein's theory of General Relativity,…
The AMANDA-II telescope at the South Pole is constructed of 677 optical modules at 19 strings. We describe the observation of atmospheric neutrinos with the first stage 10-string detector AMANDA-B10, which establishes AMANDA as a working…
In this work, an attempt is presented to understand the contribution of Galileo Galilei in the field of the History of Ideas, from the moment he points a spyglass to the sky. For that, it was previously necessary that Giotto painting the…
Three years after the launch of the Fermi Gamma-ray Space Telescope, both of its scientific instruments are operating perfectly and continuing to make breakthroughs in astrophysics, particle physics, and atmospheric science. I report here…
Galileo determined distances to stars based on the assumption that stars were suns, the apparent sizes of stars as seen through his telescope, and basic geometry. However, the apparent sizes that he measured were the result of diffraction…
The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose a detailed, pedagogical, and rigorous introduction to this coordinate system,…
In 1919, Eddington and Dyson led two famous expeditions to measure the bending of light during a total solar eclipse. The results of this effort led to the first experimental confirmation of Einstein's General Relativity and contributed to…