Sky and Telescope - June 2018 - 6
FROM OUR READERS
Up, Up, and Away
The article "Science in the Stratosphere" (S&T: Feb. 2018, p. 14) states that, to
retrieve the telescope at each mission's end, the telescope detaches from the balloon, goes into free fall, and then parachutes down to a somewhat gentle landing.
But what happens to the balloon? Does it somehow self-destruct, or does it just
eventually fall back to Earth somewhere unguided?
Kurt Petersen * Sheboygan Falls, Wisconsin
Laura Fissel replies: That is a really good question! When NASA sends a signal to
separate the balloon from the parachute, it also ﬁres explosive bolts that tear open a
large seam in the balloon so that the helium can escape. The balloon therefore falls as well,
usually landing a kilometer or so away from the telescope. It can't be used again, so NASA
personnel just collect and remove it. But it's far better to recover the balloon from nearby
than to have it land much later somewhere unexpected. You can imagine what a surprise it
would be for anyone who saw the balloon land or happened to come across it later!
Fissel's article on balloon astronomy took me back to a special evening 25 years or so
ago. I was driving home and saw a bright, planet-like object in the twilight sky where
no planet should be. It was getting dark, but I got out my telescope and pointed it
at the mystery object, and there before me was a beautiful, teardrop-shaped balloon
that was high enough to still be in sunlight. I could see the sun reﬂecting off the
instrument package dangling beneath - a sight I've never seen since.
As a subscriber since college in 1987,
I've rarely been tempted to write the
editors. However, the Spectrum entitled
"Rippled Fabric of Astronomy" (S&T:
Jan. 2018, p. 4) has led me to raise a
question about one of the key items in
While the direct observation of
a neutron-star merger in both light
and gravity waves was indeed a historic event, it's not the ﬁrst time
we've "usher[ed] in an entirely new
era of 'multi-messenger astronomy.'"
Wouldn't this new era be more accu6
J U N E 2 018 * SK Y & TELESCOPE
I want to thank Alan Whitman for his
article "Dark Clouds in Taurus" (S&T:
Jan. 2018, p. 57). The number of people
who can observe dark nebulae grows
smaller every day due to light pollution.
I had ﬁrst learned of and planned to
view the Taurus Dark Cloud complex a
few months prior but didn't have a map
good enough to ﬁnd its nebulae. With
Whitman's article in hand, I was able
to try hunting them down in my 8×56
I found all the dark nebulae that
he plotted by slowly sweeping back
and forth, looking for a lack of stars.
However, I could only catch glimpses
of that inky black at the heart of a few
dark patches. What really surprised me
was how, when I put the binoculars
down and simply gazed at the area with
averted vision, I kept glimpsing those
I conﬁrmed my naked-eye sighting by sketching where I was seeing
the two streamers and comparing it to
wide-ﬁeld images. I credit my superdark skies (limiting magnitude 7.5) and
young eyes for making such an amazing
Scott N. Harrington
Evening Shade, Arkansas
Full Moon Fever
rately dated to the detection of neutrinos and optical radiation from Supernova 1987A?
The great discoveries rarely fade with
time, and I suspect Peter Tyson's mild
hyperbole might end up being more true
than the neutrino-linked supernova
event of 30 years ago. I really enjoyed
the comparison of light and gravitywave detection for the same event as
both hearing and seeing it, though I
don't know what the neutrino equivalent would be - feeling it, perhaps?
I once thought, as Dave Chapman does,
that "if you do the math, you'll ﬁnd
that when February has no full Moons,
then both January and March that year
must contain two full Moons" (S&T:
Feb. 2018, p. 84). Alas, this is often but
not always the case, at least as reckoned
in Universal Time.
In the year 2094, for instance, it's
the months of January and April (not
January and March) that feature two
full Moons, and looking ahead to 2113,
it's January and May that sport the two
Also, it's possible for a February
with no full Moon to happen in a year
with only 12 full Moons (2067), which
means that only one month (March in
this case) gets two of them.
Anderson, South Carolina
Norwood, New York
Scott Kardel * San Marcos, California
A New Era?
Seeing in the Dark
H YSIC S T E A M / L ASP
A high-altitude balloon
carrying the HyperSpectral
Imager for Climate Science
instrument is partially inflated with helium at sunrise in
preparation for launch.