We re-examine a 50+ year-old problem of deep central reversals predicted for strong solar spectral lines, in contrast to the smaller reversals seen in observations.

In the context of the solar atmosphere, we re-examine the role of of neutral and ionized species in dissipating the ordered energy of intermediate-mode MHD waves into heat.

Philip Judge states that the interpretation of emission lines formed in large astrophysical plasmas such as the solar atmosphere faces many challenges. Relatively simple line-ratio estimates of physical parameters, while appealing, are heavily laden with assumptions.

We examine spectropolarimetric data from the CoMP instrument, acquired during the evolution of the September 10th 2017 X8.2 solar flare on the western solar limb. CoMP captured linearly polarized light from two emission lines of Fe XIII at 1074.7 and 1079.8 nm, from 1.03 to 1.5 solar radii.

We report observations of small-scale swirls seen in the solar chromosphere. They are typically 2 Mm in diameter and last around 10 minutes.

Recently published, precise stellar photometry of 72 Sun-like stars obtained at the Fairborn Observatory between 1993 and 2017 is used to set limits on the solar forcing of Earth’s atmosphere of ±4.5 W m⁻² since 1750.

We present spectra and broad-band polarized light data from a suite of instruments deployed during the 21st August 2017 total solar eclipse. Our goals were to survey solar spectra at thermal infrared wavelengths during eclipse, and to test new technology for measuring polarized coronal light.

We study visible and infrared spectra, from 310 nm to 5 microns, obtained during the 21st August 2017 eclipse. The instruments were situated at Camp Wyoba (altitude 2402 m) on Casper Mountain, WY.

A short guide to spectroscopy is given, with emphasis upon the elementary physics needed to understand and begin modeling the radiation emerging from astrophysical plasmas using the Sun as a guide, without bias towards a particular region of the Sun's atmosphere.