OrbitalHub

Wikipedia dicit:

An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. The first confirmation of detection occurred in 1992. This was followed by the confirmation of a different planet, originally detected in 1988. As of 1 January 2020, there are 4,160 confirmed exoplanets in 3,090 systems, with 676 systems having more than one planet.

There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like stars have an “Earth-sized” planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.

Video credit: NASA/JPL-Caltech

NASA dicit:

In a generic brick building on the northwestern edge of NASA’s Goddard Space Flight Center campus in Greenbelt, Maryland, thousands of computers packed in racks the size of vending machines hum in a deafening chorus of data crunching. Day and night, they spit out five quadrillion calculations per second. Known collectively as the Discover supercomputer, these machines are tasked with running sophisticated climate models to predict Earth’s future climate.

But now, they’re also sussing out something much farther away: whether any of the more than 4,000 curiously weird planets beyond our solar system — or exoplanets — discovered in the past two decades could have the ingredients necessary to support life.

Video credit: NASA’s Goddard Space Flight Center/LK Ward (USRA): Lead Producer/Claire Andreoli (NASA/GSFC): Lead Public Affairs Officer/Lonnie Shekhtman (ADNET): Lead Writer/Alex Kekesi (GST): Lead Visualizer/Anthony DelGenio (NASA/GSFC GISS): Lead Scientist/Avi Mandell (NASA/GSFC): Lead Scientist/Michael J. Way (NASA/GSFC GISS): Scientist/Chris Smith (USRA): Animator/Aaron E. Lepsch (ADNET): Technical Support/Music: “Machine Learning” by Jon Cotton and Ben Niblett; “No Wave” by Julien Vignon; “The Missing Star” by Matthew Charles Gilbert Davidson; all from Universal Production Music

NASA dicit:

NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It’s roughly 40 of the Sun’s mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission’s first year, and scientists caught multiple transits by its three planets.

The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth — between the sizes of Earth and Neptune — orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight.

Video Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger (USRA): Lead Producer/Chris Smith (USRA): Lead Animator/Jeanette Kazmierczak (University of Maryland College Park): Lead Science Writer/Gabrielle Engelmann-Suissa (USRA): Scientist/Barb Mattson (University of Maryland College Park): Narrator/Geronimo Villanueva (Catholic University of America): Visualizer

NASA dicit:

This visualization shows how ultraviolet light from the first stars and galaxies gradually transformed the universe. Hydrogen atoms, also called neutral hydrogen, readily scatters UV light, preventing it from traveling very far from its sources. Gradually, intense UV light from stars and galaxies split apart the hydrogen atoms, creating expanding bubbles of ionized gas. As these bubbles grew and overlapped, the cosmic fog lifted. Astronomers call this process reionization. Here, regions already ionized are blue and translucent, areas undergoing ionization are red and white, and regions of neutral gas are dark and opaque.

Video Credit: NASA/M. Alvarez, R. Kaehler, and T. Abel (2009)

Wikipedia dicit:

The lunar phase or phase of the Moon is the shape of the directly sunlit portion of the Moon as viewed from Earth. The lunar phases gradually change over the period of a synodic month (about 29.53 days), as the orbital positions of the Moon around Earth and of Earth around the Sun shift.

The Moon’s rotation is tidally locked by Earth’s gravity; therefore, most of the same lunar side always faces Earth. This near side is variously sunlit, depending on the position of the Moon in its orbit. Thus, the sunlit portion of this face can vary from 0% (at new moon) to 100% (at full moon). The lunar terminator is the boundary between the illuminated and darkened hemispheres.

Each of the four “intermediate” lunar phases is around 7.4 days, but this varies slightly due to the elliptical shape of the Moon’s orbit. Aside from some craters near the lunar poles, such as Shoemaker, all parts of the Moon see around 14.77 days of daylight, followed by 14.77 days of “night”.

The side of the Moon facing away from Earth is sometimes called the “dark side of the Moon”, although that is a misnomer.

Video Credit: NASA

NASA dicit:

NASA’s Parker Solar Probe mission has returned unprecedented data from near the Sun, culminating in new discoveries published on December 4, 2019, in the journal Nature. Among the findings are new understandings of how the Sun’s constant outflow of material, the solar wind, behaves. Seen near Earth — where it can interact with our planet’s natural magnetic field and cause space weather effects that interfere with technology — the solar wind appears to be a relatively uniform flow of plasma. But Parker Solar Probe’s observations reveal a complicated, active system not seen from Earth.

Video Credit: NASA’s Goddard Space Flight Center