APOD: A Prominence on the Sun (2015 Sep 19)

[APOD Robot]

A Prominence on the Sun

Explanation: This eerie landscape of incandescent plasma suspended in looping and twisted magnetic fields stretched toward the Sun's eastern horizon on September 16. Captured through a backyard telescope and narrowband filter in light from ionized hydrogen, the scene reveals a gigantic prominence lofted above the solar limb. Some 600,000 kilometers across, the magnetized plasma wall would dwarf worlds of the Solar System. Ruling gas giant Jupiter can only boast a diameter of 143,000 kilometers or so, while planet Earth's diameter is less than 13,000 kilometers. Known as a hedgerow prominence for its appearance, the enormous structure is far from stable though, and such large solar prominences often erupt.

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[Guest]

There is a mistake in the explanation. There is no light emitted by ionized hydrogen, either it should be neutral hydrogen or other species.

[Boomer12k]

There is a mistake in the explanation. There is no light emitted by ionized hydrogen, either it should be neutral hydrogen or other species.

From an Article...

The Hydrogen 21-cm Emission Line*

Gas
About 99% of the interstellar medium
(ISM) is gas: About 90% atomic or
molecular hydrogen, 10% helium, and traces
of other elements. Dust scatters and
absorbs visible light much more than a ga
s. The interstellar gas can be seen when
you look at the spectral lines of a binary
star system. Among the broad lines that
shift as the two stars orbit each other,
there are narrow lines that do not move.
The narrow lines are from much colder ga
s in the interstellar medium between us
and the binary system.
The hydrogen gas is observed in a variet
y of states: ionized, neutral atomic and
molecular forms. The ionized hydrogen emit
s visible light as the electrons combine
with the protons to form neutral hydrog
en. Both neutral atomic and molecular
hydrogen emit in the radio region
of the electromagnetic spectrum

:---[===] *

[paulslittlebit]

There is a mistake in the explanation. There is no light emitted by ionized hydrogen, either it should be neutral hydrogen or other species.

What make you thank that ionized hydrogen emitted no light?

[neufer]

There is a mistake in the explanation. There is no light emitted by ionized hydrogen, either it should be neutral hydrogen or other species.

<<While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma [including a lot of neutral hydrogen], similar in composition to that of the chromosphere.>>