APOD: Planets on the Wing (2018 Jan 06)

[APOD Robot]

Planets on the Wing

Explanation: Lately, bright Jupiter and fainter Mars have been easy to spot for early morning skygazers. Before dawn on January 7 the two naked-eye planets will reach a close conjunction near the horizon, only 1/4 degree apart in predawn eastern skies. That apparent separation corresponds to about half the angular diameter of a Full Moon. Just off the wing of a high-flying aircraft in this snapshot from early morning January 5, Jupiter (left) and Mars (middle) are also lined-up with the well-balanced Zubenelgenubi (right), alpha star of the constellation Libra. Below are lights from central Europe near Prague, Czech Republic, planet Earth.

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[ta152h0]

I have been watching " How the Universe Works " and I seem to get that Jupiter is an " almost star ".

[De58te]

No, Jupiter is just a gas giant planet. A cold Jupiter that is almost a Hot Jupiter as seen around hundreds of exoplanet systems. The reason why it is not a Hot Jupiter is because Jupiter is farther away from the Sun than Mercury is.

[BDanielMayfield]

I have been watching " How the Universe Works " and I seem to get that Jupiter is an " almost star ".

No, Jupiter is just a gas giant planet. A cold Jupiter that is almost a Hot Jupiter as seen around hundreds of exoplanet systems. The reason why it is not a Hot Jupiter is because Jupiter is farther away from the Sun than Mercury is.

That's right De58te. Jupiter is not even almost a brown dwarf; an intermediate object between planets and true stars.

Brown dwarfs are substellar objects that occupy the mass range between the heaviest gas giant planets and the lightest stars, of approximately 13 to 75–80 Jupiter masses (MJ),[1][2] or approximately 2.5×10^28 kg to about 1.5×10^29 kg. Below this range are the sub-brown dwarfs, and above it are the lightest red dwarfs (M9 V). Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth.[3]

Unlike the stars in the main-sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen (1H) to helium in their cores. They are, however, thought to fuse deuterium (2H) and to fuse lithium (7Li) if their mass is above a debated[4] threshold of 13 MJ and 65 MJ, respectively.[2] It is also debated whether brown dwarfs would be better defined by their formation processes rather than by their supposed nuclear fusion reactions.[4]

[ta152h0]

maybe we can convince the Juno spacecraft to image a Mars -Earth conjunction ?

[neufer]

maybe we can convince the Juno spacecraft
to image a Mars -Earth conjunction ?

[neufer]

Click to play embedded YouTube video.