Artist's impression of a young star surrounded by a protoplanetary disc made of gas and dust. According to new research, ring-shaped, turbulent disturbances (substructures) in the disk lead to the rapid formation of several gas and ice giants. Credit: LMU / Thomas Zankl, crushed eyes media
The most widely recognized explanation for planet formation is the accretion theory. It states that small particles in a protoplanetary disk accumulate gravitationally and, over time, form larger and larger bodies called planetesimals. Eventually, many planetesimals collide and combine to form even larger bodies. For gas giants, these become the cores that then attract massive amounts of gas over millions of years.
But the accretion theory struggles to explain gas giants that form far from their stars, or the existence of ice giants like Uranus and Neptune.
Our gleaming Earth, brimming with liquid water and swarming with life, began as all rocky planets do: dust. Somehow, mere dust can become a life-bearing planet given enough time and the right circumstances. But there are unanswered questions about how dust forms any rocky planet, let alone one that supports life.
This illustration shows what the hot rocky exoplanet TRAPPIST-1 b could look like. A new method can help determine what rocky exoplanets might have large reservoirs of subsurface water. Credits: NASA, ESA, CSA, J. Olmsted (STScI)
Astronomers know of about 60 rocky exoplanets orbiting in the habitable zones of their stars. When they try to determine how habitable these planets might be, detecting water in their atmospheres plays a huge role. But what if there was another way of measuring the water content in these worlds?
Researchers are developing a way of modelling these worlds to determine how much water they have.
The red supergiant Betelgeuse. Its activity can be confounding, and new research suggests that the star could've consumed a smaller companion star. Image credit: Hubble Space Telescope. Image Credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella
Whenever something happens with Betelgeuse, speculations about it exploding as a supernova proliferate. It would be cool if it did. We’re far enough away to suffer no consequences, so it’s fun to imagine the sky lighting up like that for months.
Now the red supergiant star has brightened by almost 50%, and that has the speculation ramping up again.
The LEGO New Glenn 2nd stage. Image Credit: Roche/Nolan
Indulge your inner man-child (or woman-child) with these LEGO versions of the Blue Origin Blue Moon lunar lander, New Glenn rocket, and launch tower. This new design is currently gathering supporters on the LEGO Ideas website. If it gets enough supporters, LEGO will review it and possibly build it.
Comet ISON is making its way through the inner solar system. Visualize its unusual orbit and track its journey
around the sun with this paper model. The background image shows comet C/2001 Q4 (NEAT). Credit: NASA and T. A. Rector (Univ. of Alaska Anchorage), Z. Levay and L. Frattare (STScI) and WIYN/NOAO/AURA/NSF
Planet orbits are so easy to picture – eight nearly concentric hula hoops centered on the sun. Comets are weirder. Their orbits vary from tapered ellipses shaped like cigars to completely open-ended parabolas and even hyperbolas. Comet ISON’s highly-elongated (stretched out) orbit is best described as hyperbolic, although that’s subject to change if Jupiter gets into the act and gives the comet a gravitational nudge during its outbound journey. As the largest planet, it has a special knack for this kind of trick, having tamed many a wayward comet’s orbit into a neat ellipse.
Comets can travel in a variety of orbits from elliptical to open-ended parabolic and hyperbolic. Credit: Wikipedia
Comets in hyperbolic and parabolic orbits are typically making their first trip to the sun from the bitterly cold and distant Oort Cloud, a roughly spherical volume of space beginning about 3,000 times Earth’s distance from the sun and extending outward to 50,000 times that distance or nearly one-quarter of the way to Alpha Centauri. The Cloud is believed to hold trillions of icy comets. Think of it as the sun’s ultimate beer cave.
To help visualize Comet ISON’s travels across the solar system we can always go the Internet and search for images and video, but sometimes it’s fun to use your own hands. Building a model using a simple cardboard template can make the knowledge “stick”. Not to mention it’s an excellent classroom activity for teachers preparing students for the comet’s post-perihelion display. All you need is this color pdf file, a printer and a few minutes to assemble.
The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets – the Oort Cloud. Credit: Wikimedia Commons
Planets’ orbits are only slightly tilted to each other, but Oort Cloud comets drop in from any angle they choose. Gravitational interactions with passing stars and clouds of interstellar gas nudge them into the inner solar system, where they’re cooked by the sun into glowing and long tails composed of vaporizing ice and dust. Long ago, some passing star gave ISON a push. It’s been falling toward the sun ever since.
Animation of Comet ISON’s orbit created by NASA
While it may be tough to picture Comet ISON’s orbit slicing the planetary racetrack at a 62-degree angle, the paper model will give you an intuitive understanding of ISON’s path and comet orbits in general.
P.S. In case you’re a klutz with a scissors just click on the Youtube video above.
