When Does "Solar, Man of the Atom" #2 (1991) Take Place?
"Solar, Man of the Atom" #2 v1 "Second Death" Part 2 "Out of My Mind" is a science fiction comic-book written by Jim Shooter that released July 19th, 1991. So when is "Solar, Man of the Atom" #2 set?
It takes place on the fictional Valiant Universe timeline in the year:
We know this because near the end of the previous issue, "Solar, Man of the Atom" #1 (1991), Doctor Phil Seleski/Doctor Solar finds something in a trash with a date (probably a recent newspaper) and reads it out-loud "September 27, 1990." So it is still late September of 1990 AD. Specifically, it is now September 28th, 1990 AD.

1990 AD
We know this because near the end of the previous issue, "Solar, Man of the Atom" #1 (1991), Doctor Phil Seleski/Doctor Solar finds something in a trash with a date (probably a recent newspaper) and reads it out-loud "September 27, 1990." So it is still late September of 1990 AD. Specifically, it is now September 28th, 1990 AD.
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"Solar, Man of the Atom" #1 also includes the story:
--The back-up feature "Alpha and Omega" Part 2 (inserted into the middle of the comic) written by Jim Shooter with Bob Layton [partially remaking "Doctor Solar, Man of the Atom" #1 v1 (1962) by Paul S. Newman].
It takes place on the fictional Valiant Universe timeline in the year:
1990? AD
We know this because in the previous issue, "Solar, Man of the Atom" #1 (1991), a sign reading "WELCOME TO MUSKOGEE" tells us we're in the real-world town of Muskogee, Oklahoma, which was founded on March 16th, 1898 AD. So it must be after March of 1898 AD.
Also, Doctor Phil Seleski comments on some visible graffiti saying, 'That sign used to say "STOP Reagan"...', referring to the real-world US President Ronald Reagan (1911-2004). Reagan announced his first campaign for the presidency on November 20th, 1975 AD. He was formerly the Governor of California from 1967 AD until 1975 AD but it's unlikely to be a reference to his policies during that time since a person in Oklahoma probably wouldn't be moved enough by policies only affecting California residents to make graffiti. So it is most likely after 1975 AD.
This story opens with Seleski as a non-superpowered human and he exhibits superpowers during the main story "Second Death" Part 2 "Out of My Mind", which takes place in late September of 1990 AD. So it must be sometime between November of 1975 AD and late September of 1990 AD.
This comic was collected as part of "Solar, Man of the Atom" #0.