Planets in our own solar system have a wide range of properties. They are distinguished by two basic properties, their size and their orbit. The size determines if the planet can have a life-sustaining atmosphere. The orbit affects the surface temperature and whether there could be liquid water on the planet’s surface.
Hot Jupiters are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital period (P<10 days). The close proximity to their stars and high surface-atmosphere temperatures resulted in the moniker “hot Jupiters”.
Hot Jupiters are the easiest extrasolar planets to detect via the radial-velocity method, because the oscillations they induce in their parent stars’ motion are relatively large and rapid compared to those of other known types of planets.
One of the best-known hot Jupiters is 51 Pegasi b. Discovered in 1995, it was the first extrasolar planet found orbiting a Sun-like star. 51 Pegasi b has an orbital period of about 4 days.
There are two general schools of thought regarding the origin of hot Jupiters: formation at a distance followed by inward migration and in-situ formation at the distances at which they’re currently observed. The prevalent view is migration.
Migration
In the migration hypothesis, a hot Jupiter forms beyond the frost line, from rock, ice, and gases via the core accretion method of planetary formation. The planet then migrates inwards to the star where it eventually forms a stable orbit. The planet may have migrated inwar.
In situ
Instead of being gas giants that migrated inward, in an alternate hypothesis the cores of the hot Jupiters began as more common super-Earths which accreted their gas envelopes at their current locations, becoming gas giants in situ. The super-Earths providing the cores in this hypothesis could have formed either in situ or at greater distances and have undergone migration before acquiring their gas envelopes.
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Picture of the Day - October 18, 2018.
Sunset on an alien moon.
Picture of the day - November 22, 2018
Crescent of a moon against the silhouette of a green gas giant.
Pictures of the Day - December 25, 2018 (Merry Christmas)
Insight A-VIII is the eighth planet orbiting Insight A. It is an ice-giant with a mass 15.46 times that of Earth, and a diameter of 3.19 Earths. The planet has unusually pronounced cloud bands, and a wide-spaced ring system. It orbits it’s sun at an average distance of 4.01 AU, completing 1 orbit every 7.41 Years.
This planet has an active atmosphere with an average temperature of -213 F, and a day on the planet last 11 hours and 6 minus. 5 moons orbit the planet that are large enough to be rounded by their own gravity, including 4 larger than 2,000 kilometers across.
Insight A-VIII
Transiting Moon
Closeup
Asteroid Moon
View from outer-most large moon
Picture of the day - February 6, 2019 - (Very late post)
Ringed ocean world with greenish-gray colored oceans. The Carina Nebula fills the sky in the background.
Picture of the day - November 16, 2018
An Earth-Moon analog.
In honor of NASA’s successful landing of the InSight Lander, here are a couple of Space Engine pictures of Mars centered on the Elysium Planitia.
Had to take a second closer picture since Phobos got in the way of the first picture.
Picture 1
Picture 2
Mercury is the closest planet to the sun. As such, it circles the sun faster than all the other planets, which is why Romans named it after their swift-footed messenger god. He is the god of financial gain, commerce, eloquence, messages, communication (including divination), travelers, boundaries, luck, trickery and thieves; he also serves as the guide of souls to the underworld
Like Venus, Mercury orbits the Sun within Earth’s orbit as an inferior planet, and never exceeds 28° away from the Sun. When viewed from Earth, this proximity to the Sun means the planet can only be seen near the western or eastern horizon during the early evening or early morning. At this time it may appear as a bright star-like object, but is often far more difficult to observe than Venus. The planet telescopically displays the complete range of phases, similar to Venus and the Moon, as it moves in its inner orbit relative to Earth, which reoccurs over the so-called synodic period approximately every 116 days.
Mercury’s axis has the smallest tilt of any of the Solar System’s planets (about 1⁄30 degree). Its orbital eccentricity is the largest of all known planets in the Solar System; at perihelion, Mercury’s distance from the Sun is only about two-thirds (or 66%) of its distance at aphelion.
Its orbital period around the Sun of 87.97 days is the shortest of all the planets in the Solar System. A sidereal day (the period of rotation) lasts about 58.7 Earth days.
Mercury’s surface appears heavily cratered and is similar in appearance to the Moon’s, indicating that it has been geologically inactive for billions of years. Having almost no atmosphere to retain heat, it has surface temperatures that vary diurnally more than on any other planet in the Solar System, ranging from 100 K (−173 °C; −280 °F) at night to 700 K (427 °C; 800 °F) during the day across the equatorial regions. The polar regions are constantly below 180 K (−93 °C; −136 °F). The planet has no known natural satellites.
Unlike many other planets which “self-heal” through natural geological processes, the surface of Mercury is covered in craters. These are caused by numerous encounters with asteroids and comets. Most Mercurian craters are named after famous writers and artists. Any crater larger than 250 kilometres in diameter is referred to as a Basin.
The largest known crater is Caloris Basin, with a diameter of 1,550 km. The impact that created the Caloris Basin was so powerful that it caused lava eruptions and left a concentric ring over 2 km tall surrounding the impact crater.
Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975; and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet’s surface on April 30, 2015.
It is the smallest planet in the Solar System, with an equatorial radius of 2,439.7 kilometres (1,516.0 mi). Mercury is also smaller—albeit more massive—than the largestnatural satellites in the Solar System, Ganymede and Titan.
As if Mercury isn’t small enough, it not only shrank in its past but is continuing to shrink today. The tiny planet is made up of a single continental plate over a cooling iron core. As the core cools, it solidifies, reducing the planet’s volume and causing it to shrink. The process crumpled the surface, creating lobe-shaped scarps or cliffs, some hundreds of miles long and soaring up to a mile high, as well as Mercury’s “Great Valley,” which at about 620 miles long, 250 miles wide and 2 miles deep (1,000 by 400 by 3.2 km) is larger than Arizona’s famous Grand Canyon and deeper than the Great Rift Valley in East Africa.
The first telescopic observations of Mercury were made by Galileo in the early 17th century. Although he observed phases when he looked at Venus, his telescope was not powerful enough to see the phases of Mercury.
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images: Joseph Brimacombe, NASA/JPL, Wikimedia Commons
Pictures of the Day - December 15, 2018
Insight A-II is the second planet orbiting Insight A. It is a Venus-like planet shrouded in a thick carbon dioxide and water vapor atmosphere 716 times thicker than Earth’s. The surface temperature averages 1,980 F, and most of the surface is covered in molten rock.
The planet orbits just 0.07 AU from the sun, completing an orbit once every 6.72 Earth days. Insight A-II is a super-earth with a mass 2.66 times that of Earth and a radius of 1.15 Earths.
Insight A-II
Comet-like planet
The Atmosphere
The Surface
Pictures of the day - February 10, 2019 (Late post).
Montage of lunar skies.
Picture of the day 2 - January 10, 2019
Warm gas giant surrounded by a rainbow-colored ring system.
Space Engine System ID: RS 8550-1391-7-1315996-265 4 to visit the planet in space engine.
My Space Engine Adventures, also any space related topic or news. www.spaceengine.org to download space engine. The game is free by the way. Please feel free to ask me anything, provide suggestions on systems to visit or post any space related topic.Check out my other blog https://bunsandsharks.tumblr.com for rabbit and shark blog.
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