Related papers: The edge of space: Revisiting the Karman Line
The shell bound by the Karman line at a height of 80 to 100km above the Earth's surface, and Geosynchronous Orbit, at 36,000km, is defined as the orbital space surrounding the Earth. It is within this region, and especially in Low Earth…
Whether there is a cosmic shoreline that divides terrestrial planets which have atmospheres from those that don't is one of the biggest open questions in exoplanet science. Most atmosphere searches have focused on terrestrial planets around…
We significantly constrain the sky position, distance, and mass of a possible additional, distant planet in the solar system by examining its influence on the distance between Earth and the Cassini Spacecraft. Our preferred region is…
Various ``cosmic shorelines" have been proposed to delineate which planets have atmospheres. The fates of individual planet atmospheres may be set by a complex sea of growth and loss processes, driven by unmeasurable environmental factors…
The quest for other habitable worlds and the search for life among them are major goals of modern astronomy. One way to make progress towards these goals is to obtain high-quality spectra of a large number of exoplanets over a broad range…
We give estimates on the length of paths defined in the sphere model of outer space using a surgery process, and show that they make definite progress in some sense when they remain in some thick part of outer space. To do so, we relate the…
We prove that the boundary of an orbit space or more generally a leaf space of a singular Riemannian foliation is an Alexandrov space in its intrinsic metric, and that its lower curvature bound is that of the leaf space. A rigidity theorem…
A key item of interest for planetary scientists and astronomers is the habitable zone, or the distance from a host star where a terrestrial planet can maintain necessary temperatures in order to retain liquid water on its surface. However,…
Some tests of gravity theories - periastron shift, geodetic precession, change in mean motion and gravitational redshift - are applied in solar and stellar systems to constrain the cosmological constant. We thus consider a length scale…
Studies of planetary atmospheric composition, variability, and evolution require appropriate theoretical and numerical tools to estimate key atmospheric parameters, among which the mass-loss rate is often the most important. In evolutionary…
The large-scale structure of the Universe is well approximated by the Friedmann equations, parametrized by several energy densities which can be observationally inferred. A natural question to ask is: How different would the Universe be if…
The goal of the paper is to study the angle between two curves in the framework of metric (and metric measure) spaces. More precisely, we give a new notion of angle between two curves in a metric space. Such a notion has a natural interplay…
Observations of interstellar gas and dust towards nearby stars and within the solar system show that the Sun is embedded in a warm diffuse partially-ionized cloud. This cloud is the leading edge of a flow of interstellar matter (ISM)…
We consider the problem of distance between two particles in the universe, where space is taken to be Liebnizian rather than Newtonian, this being the present day approach. We then argue that with latest inputs from physics, it is possible…
Characterizing the Martian atmosphere is an essential objective to understand its meteorology and its climate. The lower atmosphere (< 40 km) and middle atmosphere (40-80 km) of Mars appear dynamically coupled at much higher levels than in…
It is still uncertain whether the cosmic censorship conjecture is true or not. To get a new insight into this issue, we propose the concept of the border of spacetime as a generalization of the spacetime singularity and discuss its…
The infrared sky from space is the sum of a cosmic signal from galaxies, quasars, and perhaps more exotic sources; and foregrounds from the Milky Way and from the Solar System. At a distance of 1 AU from the Sun, the foreground from…
The "cosmic shoreline," a semi-empirical relation that separates airless worlds from worlds with atmospheres as proposed by K. J. Zahnle & D. C. Catling, is now guiding large-scale JWST surveys aimed at detecting rocky exoplanet…
The Galactic plane has been mapped from l=34.75d to 45.25d and b=-5.25d to 5.25d in the CO (J=1-0) emission with the 13.7 m telescope of the Purple Mountain Observatory. The unbiased survey covers a large area of 100 square degrees sampled…
The varied surfaces and atmospheres of planets make them interesting places to live, explore, and study from afar. Unfortunately, the great distance to exoplanets makes it impossible to resolve their disk with current or near-term…