Sky and Telescope - July 2018 - 7
Your "Space Missions in 2018" summary (S&T: Jan. 2018, p. 16) omits
some space weather and other missions.
I noticed that these missions were also
absent from the list the previous year,
and since there have been no corrections, I thought it time to send this
The most notable omissions are
NASA's Van Allen Probes, two satellites studying Earth's radiation belts, as
well as the Magnetospheric Multiscale
(MMS) mission, four spacecraft moving through Earth's magnetosphere in
highly elliptical orbits.
According to the list at science.nasa.
gov/missions-page, TWINS and Geotail, other space weather missions, are
also still operational. Other missions
on this list that are still operational
are MESSENGER, AIM, and GRACE, as
well as other Earth observation satellites. I have used GRACE data for space
weather studies on how much auroral
currents heat and expand the thermosphere. I also use data from TIMED,
another NASA mission that is presently
There are also ESA's three Swarm
swarm) that I'm currently using for
space weather research, mainly for
measuring auroral currents and atmospheric density.
Camille Carlisle replies: Thank
you for pointing out these omissions. I went back through my notes and
found MMS and Geotail on my original list,
but somehow they never made it into the
spreadsheet used to create the illustration.
I'll make sure we include them when creating next year's list.
It was a treat to read Michelle Larson's article on the Adler Planetarium
entitled "#LookUp with Us" (S&T: Mar.
2018, p. 64).
In October 1947 I was beginning
studies at the University of Chicago,
and one of my ﬁrst trips downtown
was a visit to the Adler. The topic of the
lecture I attended was "Entropy," and
the lecturer was a fellow in astronomy
at Chicago named Gerard Kuiper. It was
FOR THE RECORD
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75, 50 & 25 YEARS AGO by Roger W. Sinnott
º July 1943
Blue Moon "This month's question is from Mrs. H. W. Shimer, of
"Q. Can you tell me anything about
a 'blue moon'?
"A. There are at least two possible
origins of this expression. The more
elaborate is given in the Maine
Farmers' Almanac for 1937. 'The
moon usually comes full twelve
times in a year, three times in each
season. . . . [But] occasionally the
moon comes full thirteen times
in a year. This was considered a
very unfortunate circumstance. . . .
Also this extra moon had a way of
coming in each of the seasons so
that it could not be given a name
appropriate to the time of year like
the other moons. It was usually
called the Blue Moon."
Columnist Laurence J. Laﬂeur
failed to give a speciﬁc example,
thereby paving the way for the
now-famous error, three years later,
where another S&T contributor
thought the term referred to the
second full Moon in a month (see
º July 1968
Novae Compared "A rare spectacle occurred in the spring sky this
year: two naked-eye novae were
simultaneously visible less than
20 degrees apart. They had been
discovered by the same English
amateur, G. [George E. D.] Alcock
- Nova Delphini on July 8, 1967,
Nova Vulpeculae on April 15, 1968.
"At McDonald Observatory
in Texas, Brian Warner used the
82-inch Otto Struve reflector to
photograph the spectra of both
novae on the same night, April 20,
1968, when the stars were of about
magnitude 5. The Vulpecula object
had passed maximum just three
days before [while the other was]
nine months after its outburst. . . .
"The [spectra] look very different, the Delphinus one . . . having
generally narrower emission lines
than the Vulpecula star, which has
a very complex spectrum."
º July 1993
Oddest Comet "I swung the
[18-inch Palomar Schmidt] to our
next search area, then sneered
as a bright glow almost swamped
the view in the telescope's finder.
'Dollars to doughnuts,' I cried out,
'Jupiter's in this field!' Nevertheless, we took three exposures
of the region before the clouds
thickened. . . .
"[Studying the images later,]
suddenly Carolyn straightened up
in her chair. 'I don't know what this
is,' she said. 'It looks like . . . like a
"Indeed, hovering amid the stars
was the strangest object we had
ever seen. It looked like a comet, all
right, but instead of having a nice
round coma, this one was rectangular! Was it a light streak? No,
because it appeared on both films."
David Levy, with Gene and
Carolyn Shoemaker, had just found
Comet Shoemaker-Levy 9. They
didn't yet know that just a year later
the enigmatic object would crash
right into Jupiter itself.
s k y a n d t e l e s c o p e . c o m * J U LY 2 0 1 8