Starship Asterisk*

DL MARTIN wrote: ↑Thu May 14, 2020 3:43 pm Why did the discussion for May 13 appear?

John Zelada wrote: ↑Wed May 13, 2020 10:35 pm What are Jupiter's gases made of? is it purely gaseous or is there a solid surface?

Wikipedia wrote:

Jupiter was expected to either consist of a dense core, a surrounding layer of liquid metallic hydrogen (with some helium) extending outward to about 78% of the radius of the planet, and an outer atmosphere consisting predominantly of molecular hydrogen, or perhaps to have no core at all, consisting instead of denser and denser fluid (predominantly molecular and metallic hydrogen) all the way to the center, depending on whether the planet accreted first as a solid body or collapsed directly from the gaseous protoplanetary disk.

However, the Juno mission, which arrived in July 2016, found that Jupiter has a very diffuse core, mixed into the mantle. A possible cause is an impact from a planet of about ten Earth masses a few million years after Jupiter's formation, which would have disrupted an originally solid Jovian core.

Chris Peterson wrote: ↑Wed May 13, 2020 1:40 pm

4.7 micrometers is thermal radiation- the Sun emits very little energy at that wavelength. I think what we're seeing is coming from the planet itself.

• ~4.7 µm for Jupiter
  & 3.9 µm for the Earth.

orin stepanek wrote: ↑Wed May 13, 2020 11:14 am JupiterIR_Gemini_960.jpg


Looks like light coming from within the planet! 8-)

https://en.wikipedia.org/wiki/Lucky_imaging wrote:

Click to play embedded YouTube video.

<<In 2007 astronomers at Caltech and the University of Cambridge announced the first results from a new hybrid lucky imaging and adaptive optics (AO) system. The new camera gave the first diffraction-limited resolutions on 5 m-class telescopes in visible light. The research was performed on the Mt. Palomar Hale telescope of 200-inch-diameter aperture. The telescope, with lucky cam and adaptive optics, pushed it near its theoretical angular resolution, achieving up to 0.025 arc seconds for certain types of viewing. Compared to space telescopes like the 2.4 m Hubble, the system still has some drawbacks including a narrow field of view for crisp images (typically 10" to 20"), airglow, and electromagnetic frequencies blocked by the atmosphere.

When combined with an AO system, lucky imaging selects the periods when the turbulence the adaptive optics system must correct is reduced. In these periods, lasting a small fraction of a second, the correction given by the AO system is sufficient to give excellent resolution with visible light. The lucky imaging system averages the images taken during the excellent periods to produce a final image with much higher resolution than is possible with a conventional long-exposure AO camera.

This technique is applicable to getting very high resolution images of only relatively small astronomical objects, up to 10 arcseconds in diameter, as it is limited by the precision of the atmospheric turbulence correction. It also requires a relatively bright 14th-magnitude star in the field of view on which to guide. Being above the atmosphere, the Hubble Space Telescope is not limited by these concerns and so is capable of much wider-field high-resolution imaging.>>