Sky and Telescope - July 2018 - 6
FROM OUR READERS
It was a pleasure to read about the
early days of the Riverside Telescope
Maker's Conference (S&T: Feb. 2018,
p. 64). I attended the ﬁrst one in 1969,
as a student in the Citrus College
optics program. A year later I joined
Chabot Observatory's Telescope Makers' Workshop under the mentorship
of Paul Zurakowski (Frank Wright
started the workshop in the 1930s).
Paul was instrumental in inﬂuencing
many of the students who are pictured
in the article.
For more than 30 years Paul and I
were on the team of RTMC judges and
together inspected at least a thousand telescopes. For our efforts we
both received the Clifford W. Holmes
Award; Paul got the very ﬁrst one in
1978. Students from the workshop
went on to earn many merit awards
and serve as judges over the years.
We hope RTMC will continue for
another 50 years; young people need
its pathway into science careers under
the STEM programs. Perhaps one will
be encouraged to become an optical
engineer or astronomer.
Although I did not attend the earliest
RTMC gatherings at Riverside Community College, I went to two at the
Idyllwild site, probably in 1973 and
1974. From personal experience, the
story of John Dobson sleeping in his
telescope tube is true.
I had driven a short distance from
the main area to a turnout said to give
a view of the Hale Telescope's dome
on nearby Palomar Mountain. Pulling
into the site, I noticed a school bus
and a large tube on the ground next to
it. Dobson was just emerging from the
front of the tube and said he was just
getting up for the day. I believe that
this experience conﬁrms the story.
The tube was huge, and I later realized that it was for his 24-inch Newtonian reﬂector. He had to remove the
diagonal to enter, and he showed me
how he remounted it for viewing. The
diagonal was on a wooden cross, ﬁtted to be pressed to the inside of the
tube and then pulled into place while
looking through the eyepiece holder. I
had some nice deep-sky views with the
instrument that evening.
Robert Schalck * North Bend, Oregon
Michael O'Neal * Blue Jay, California
p John Dobson's 24- and 22-inch reflectors tower over participants at the 1978 Riverside
Telescope Maker's Conference near Big Bear, California. It was the ATM community's first major
encounter with Dobson and his big scopes, which were brought to the conference by the San
Francisco Sidewalk Astronomers.
J U LY 2 0 1 8 * S K Y & T E L E S C O P E
Regarding Earth's changing magnetic
ﬁeld (S&T: Mar. 2018, p. 16), if the existence of Earth's robust magnetic ﬁeld
is vital to making our planet habitable,
yet it took a freak event to stir the mix
(the collision that produced the Moon),
then a new sub-variable would need to
be added to the Drake equation, namely,
the odds that such an event would happen and the planet also survives.
Intelligent life seems to be growing
ever more improbable!
Somerset, New Jersey
So Far and Yet So Near
In the Spectrum column "Lonely
Wanderer" (S&T: Feb. 2018, p. 4),
Peter Tyson refers to the newly discovered interstellar visitor 'Oumuamua
as a "near-Earth object." This seems
reasonable, as this asteroidal object's
perihelion was 0.255 astronomical
unit (on September 9, 2017), and the
ofﬁcial deﬁnition of NEOs is "asteroids
and comets with perihelion distance q
less than 1.3 au" (cneos.jpl.nasa.gov/
However, NASA also adds the following proviso: "Near-Earth Comets
(NECs) are further restricted to include
only short-period comets (i.e., orbital
period P less than 200 years)." It seems
to me that the same proviso was not
applied to near-Earth asteroids simply because an asteroid coming from
beyond the asteroid belt, not to mention beyond the solar system, was never
Presumably, whatever reasoning led
to the restriction in the case of comets would apply as well to asteroids.
Therefore 'Oumuamua is not, strictly
speaking, a near-Earth object.
But why did NASA include the
restriction on comets in the ﬁrst place?
Did the dictates of planetary defense
trump astronomy (or common sense),
and long-period comets were deemed
too rare or too large to defend against,
given present technological and economic constraints?
S&T / DENNIS DI CICCO
Down by the Riverside