if the great filter is behind us because early life has trouble to keep planets in the right temperature range (mars: too cold, venus: too hot) then that’s good news for our extinction risk.
Tag: planets
Super-Earth in our solar system?
It doesn’t seem to be part of the Proxima Centauri system, it must be closer and correspondingly smaller. With just 2 observations it isn’t possible to determine the object’s orbit, so we can only guess at its distance and size. One possibility (and the one I think most likely) is that it’s an extreme trans-Neptunian object ~100 astronomical units away from the Sun, which is further than Sedna at 86 AU. This would make it the most distant known object in the solar system, but likely smaller than Pluto.
Another possibility (which seems more likely to the object’s discoverers) is that it is ~300 AU away and ~1.5 times the size of Earth, making it the first “super-Earth” found in our solar system. Observations of trans-Neptunian objects have led to some speculation that 1 or 2 super-Earths could lurk in the outer solar system, so it’s not out of the question. There’s reason to be cautious of this idea, however, because of its location. Proxima Centauri is ~42 degrees away from the ecliptic. Most large solar system lay within a few degrees of the ecliptic, and even Sedna’s orbit is only inclined ~12 degrees from it.
A third possibility is that the object is a cool brown dwarf ~20k AU away. Such an object should also be visible in the infrared, so there would still be the question as to why it wasn’t discovered by earlier infrared sky surveys. Its proximity to Proxima Centauri would seem to make such an object easy to find.
Exoplanets visualization
a lot of creative license (i very much doubt we have that high res pictures from any exoplanets) but the sizes and temperatures should be correct.
Pluto
That flyby was far too quick.
2015-07-17: Animated Flyover
2015-07-24: Pluto’s atmosphere
Taken when New Horizons was about 2m kilometers past Pluto, when the tiny rock and ice world was very nearly between the spacecraft and the Sun. New Horizons looked over its shoulder, back at Pluto, to capture this breathtaking picture. The ring of light you are seeing? That’s Pluto’s atmosphere! Light passing through that cold, thin, nitrogen gas gets scattered, bent, and we see it as a halo surrounding the night side of Pluto.
2015-09-20: very nice Pluto picture.
New Horizons
After traveling ~5b km over the past 9.5 years, NASA’s New Horizons spacecraft is within hours of its rendezvous with Pluto. Back in 2006, when the space probe was launched, Pluto was classified as the 9th planet in the solar system, and was known to have 3 moons. During the long journey to this distant icy world, Pluto was reclassified as a dwarf planet, 1 of many smaller bodies orbiting the sun, and another 2 moons were discovered. In 2007, New Horizons flew past Jupiter and its moons on the way to Pluto, capturing many spectacular images. On the morning of July 14, 2015, New Horizons will speed past the Pluto system at ~14 kilometers per second, making as many observations as possible. In the hours and days following, it will be sending the data to Earth, on its way to the Kuiper belt, with plans to target another smaller body sometime around 2018.
Helium-Filled Planets
Lots of exoplanets may have helium-rich atmospheres. We don’t have any planets like this in our solar system, so this is something of a surprise. They would look decidedly odd to our eyes. Instead of the deep rich colors of our gassy planets, these helium planets would be somewhat colorless, gray or white.
12 ga planets
PSR B1620-26 b is an extrasolar planet located 12k light-years away from Earth in the constellation of Scorpius. it is one of the oldest planets in the universe, at 12.7 ga
Can life survive for billions of years longer than the expected timeline on Earth? As scientists discover older and older solar systems, it’s likely that before long we’ll find an ancient planet in a habitable zone. Knowing if life is possible on this exoplanet would have immense implications for habitability and the development of ancient life
Mars pictures
best enjoyed with Exodus
The Indian Mars Orbiter Mission (MoM) may have been modest in cost, but it carries real scientific instruments… and moreover orbits high enough in its apoapsis to start a pipeline of full-hemisphere images never before available. See the first of these. Amazing. MOM… turned around… is WOW!
Ultimate solar system
we’re about a factor 10x off from an ideal solar system
2 of our chosen stars on a wide orbit. Each hosts 1 of the systems we just built. That makes a total of 60 habitable worlds in a single system! 24 in ultimate system 1 and 36 in ultimate system The ultimate Solar System makes a great setting for storytelling. Just imagine! Wars between moons orbiting the same gas giant planet. Coalitions, alliances, trickery! High-end worlds with their own dedicated beach moons. Worlds launching long-range missiles at their Trojan counterparts. Intelligent beings who learn orbital dynamics at a very young age. Prison worlds that revolt! Plus, if 1 species took over all of the worlds orbiting 1 of the stars, there could be a whole other series of battles with the worlds orbiting the other star.
Torus Earth
what a donut planet would be like.
Can toroid planets exist? It is not obvious that a toroid planet is stable.
For all practical purposes planets are liquid blobs with no surface tension: the strength of rock is nothing compared to the weight of a planet. Their surfaces will be equipotential surfaces of gravity plus centrifugal potential. If they were not, there would be some spots that could reduce their energy by flowing to a lower potential. Another obvious fact is that there exists an upper rotation rate beyond which the planet falls apart: the centrifugal force at the equator becomes larger than gravity and material starts to flow into space.
Gregor J. Rothfuss 