Of late the UFO community has gone into a frenzy over some papers written by astronomer Beatriz Villarroel (with co-author Steven Bruehl, also Gary Nolan, and others), claiming to have found "transients" on Palomar Sky Survey plates taken (mostly) between 1949 and 1957. These are being interpreted as something mysterious, probably aliens putting things in geosynchronous orbit, objects that have since disappeared.
A good summary of Dr. Villarroel's methods is in this paper by Isabela Melamed, Not Seeing the Star Cloud for the Stars. She writes,
Within a 10×10 arcminute section — about the size of a dime held at arm’s length — they spotted nine stars, only to see them disappear 30 minutes later in the subsequent blue-sensitive plate.
This was bizarre — stars don’t vanish that fast. No known phenomenon explains it. Villarroel proposed a bold hypothesis: could the nine transients be reflections from non-terrestrial artifacts in geosynchronous orbit, perhaps extraterrestrial?
Caption from Dr. Villarroel's paper: "Four exposures of the 3 ×3 arcmin region of sky centered on the triple transient identified in July 1952. Upper left: The POSS I red image on July 19, 1952 at 8:52 (UT) containing the triple transient just above center. Upper right: A 10 m exposure POSS I blue image of the same region taken immediately afterward with no evidence of the triple transient. Lower left and right: POSS I red (left) and blue (right) images taken two months later (September 14, 1952) showing the transient still gone. Adapted from Solano et al. (2024)."
Frankly, anyone using that argument for the existence of anomalies obviously does not understand why the Palomar Sky Survey (and many others) imaged in red and blue. Astronomers want to determine the "Color Temperature" of individual stars, which reveals a lot about the star's makeup. The astronomer measures the apparent brightness of a star in red and blue light. Then the calculation of B-V (blue minus red) brightness tells us what category this star belongs to.
It is not surprising at all that some stars seen on the red-sensitive plate do not appear on the blue-sensitive plate, and vice-versa. Very red stars (type M) emit very little light in the blue part of the spectrum, and probably would not be seen on the blue-sensitive plate. The same would be true of stars Type O or B, which would probably be faint or invisible on the red-sensitive plate.
I am wondering if Dr. Villarroel or her colleagues performed the obvious, reverse search. That is, examine the blue-sensitive plate for "transients" that do not appear on the red.
When I was taking astronomy classes at Northwestern about a hundred years ago, we learned the following phrase to help us remember the different spectral types of stars:
O, Be a Fine Girl, Kiss Me.
You can't say that any more!
