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Ground-based optical astronomy necessarily involves sensing the light of astronomical objects along with the contributions of many natural sources ranging from the Earth's atmosphere to cosmological light. In addition, astronomers have long…

Instrumentation and Methods for Astrophysics · Physics 2022-08-31 John C. Barentine

The horologia are ancient ephemerides, tables of durations of the days and nights during all months of the year. The algorithms used to compute the horologia are here presented and the results are compared with the tables computed by…

History and Philosophy of Physics · Physics 2012-11-13 Costantino Sigismondi

The gravitational field of the sun will focus light from a distant source to a focal point at a minimal distance of 550 Astronomical Units from the sun. A proposed mission to this gravitational focus could use the sun as a very large lens,…

Earth and Planetary Astrophysics · Physics 2016-12-15 Geoffrey A. Landis

We show that the visual angle metric and the triangular ratio metric are comparable in convex domains. We also find the extremal points for the visual angle metric in the half space and in the ball by use of a construction based on…

Metric Geometry · Mathematics 2018-01-29 Parisa Hariri , Matti Vuorinen , Gendi Wang

We report spectroscopic observations of the earthshine reflected from the Moon. By applying our photometry methodology to spectroscopy, we were able to precisely determine the Earth's reflectance, and its variation as a function of…

Astrophysics · Physics 2009-11-11 P. Montanes-Rodriguez , E. Palle , P. R. Goode , J. Hickey , S. E. Koonin

It is known from theory that, by means of a plasma physics approach, it is possible to obtain a simple formula to calculate the approximate height of a meteor (Foschini, 1999). This formula can be used in case of forward scatter of radio…

Astrophysics · Physics 2007-05-23 A. Carbognani , M. De Meyere , L. Foschini , C. Steyaert

Theorists are often told to express things in the "observational plane". One can do this for space-time geometry, considering "visual" observations of matter in our universe by a single observer over time, with no assumptions about…

General Relativity and Quantum Cosmology · Physics 2012-11-20 Albert Stebbins

The active broadband (1 kHz-100 MHz) tripole antenna now envisaged to be placed on the European Lunar Lander located at the Lunar South Pole allows for sensitive measurements of the exosphere and ionosphere, and their interaction with the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Marc Klein Wolt , Amin Aminaei , Philippe Zarka , Jan-Rutger Schrader , Albert-Jan Boonstra , Heino Falcke

A human-robotic "Moon Village" would offer significant scientific opportunities by providing an infrastructure on the lunar surface. An analogy would be the way in which human outposts in Antarctica facilitate research activities across…

Earth and Planetary Astrophysics · Physics 2017-06-22 Ian A. Crawford

We address three major questions in astronomy, namely the detection of biosignatures on habitable exoplanets, the geophysics of exoplanets and cosmology. To achieve this goal, two requirements are needed. First a very large aperture to…

Earth and Planetary Astrophysics · Physics 2019-08-07 J. Schneider , J. Silk , F. Vakili , I. Crawford , M. Elvis , S. Jacquemoud , R. Kaiser , M. Sandora

In the Tuscan Archipelago (Italy) it's possible to make an approximate measurement of the Earth's radius from the Elba Island using the Pianosa Island as a ship that appears and disappears on the horizon depending on the observer's height…

Physics Education · Physics 2023-12-18 Davide Neri

The non-spherical shape of the Sun has been invoked to explain the anomalous precession of Mercury. A brief history of some methods for measuring solar diameter is presented. Archimedes was the first to give upper and lower values for solar…

History and Philosophy of Physics · Physics 2009-11-11 Costantino Sigismondi , Pietro Oliva

Supportive attitudes can bring to a blossoming science, while neglect can quickly make science absent from everyday life and provide a very primitive view of the world. We compare one important Greek achievement, the computation of the…

History and Overview · Mathematics 2012-05-07 Khristo N. Boyadzhiev

When the Moon was formed it was much closer to the Earth than it is today. It just needed about 20 days then to go around the Earth. Now it takes the Moon 29.5 days to make one revolution. In order to follow the conservation of angular…

General Physics · Physics 2016-09-08 Sohail Alam , B. K. Sharma

This paper presents a method of estimating the geometry of a room and the 3D pose of objects from a single 360-degree panorama image. Assuming Manhattan World geometry, we formulate the task as a Bayesian inference problem in which we…

Computer Vision and Pattern Recognition · Computer Science 2016-10-03 Jiu Xu , Bjorn Stenger , Tommi Kerola , Tony Tung

Metric magnitude is a measure of the "size" of point clouds with many desirable geometric properties. It has been adapted to various mathematical contexts and recent work suggests that it can enhance machine learning and optimization…

Machine Learning · Computer Science 2024-09-09 Rayna Andreeva , James Ward , Primoz Skraba , Jie Gao , Rik Sarkar

A smartphone is a powerful learning aid in the hands of a large section of students around the world. The camera of the phone can be used for several learning purposes apart from its obvious purpose of photographing. If the focal length of…

Physics Education · Physics 2022-08-11 Soumen Sarkar , Sanjoy Kumar Pal , Surajit Chakrabarti

Many science missions require an unobstructed view of space and a stable thermal environment but lack the technical or programmatic resources to reach orbits that satisfy these needs. This paper presents a high Earth orbit in 2:1 resonance…

Earth and Planetary Astrophysics · Physics 2013-08-09 Joseph W. Gangestad , Gregory A. Henning , Randy R. Persinger , George R. Ricker

With a sky brightness monitor in Xinglong station of National Astronomical Observatories of China (NAOC), we collected data from 22 dark clear nights and 90 lunar nights. We first measured the sky brightness variation with time in dark…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 Song Yao , Hao-Tong Zhang , Hai-Long Yuan , Yong-Heng Zhao , Yi-Qiao Dong , Zhong-Rui Bai , Li-Cai Deng , Ya-Juan Lei

In this work, we address the effects of a phenomenon known as Verlinde gravity. Here we show that its effect over the planets and the Moon in our solar system is quite negligible. We find that the Verlinde gravity effects on the orbits of…

General Relativity and Quantum Cosmology · Physics 2020-05-13 Youngsub Yoon , Luciano Ariel Darriba