Page 61 - Astronomy - October 2017 USA

Measure up Dome globe lights Street non-full-cutoff lights Square full-cutoff lights
Background stars

Distance star
appears to move

Star
1 parsec (3.26 ly) Parallax Light pollution can be easier to explain once you’re familiar with the different types of shielding that
manufacturers make for lights.

angle
1 arcsecond
Eclipsing
Line of sight from Earth
Penumbra
Earth
Partial eclipse begins
Sun
1:58 A.M. EDT
Umbra
When someone asks you, “How do
astronomers know how far away stars Totality ends
are?” you’ll have to introduce them 4:25 A.M. EDT
to tiny angles and the word parallax. Penumbral
eclipse ends
6:38 A.M. EDT Penumbral
eclipse begins
is present, use its focal length and 12:54 A.M. EDT
that of the eyepiece currently in it
Totality begins
to figure out the power. That will
3:07 A.M. EDT
bring home the concept in a more Partial eclipse ends
concrete way. 5:33 A.M. EDT
An illustration explaining mag-
nification could start with the This chart demonstrates how lunar eclipses occur in an easy-to-follow format.
statement, “A power of X is like
being X times closer to something.”
Explain that 7x binoculars make to a non-astronomy-savvy friend or, if we must use strange terminol-
objects appear seven times closer. who just asked you to define right ogy, we’ll provide definitions, often
Then pick an object. Select a big ascension (probably because you in the same sentence.
one but not an immense one. So, used it in a sentence without think- Oh, and in case you’re wonder-
pick a car but not a building, a bush ing about it). How much detail ing, after many years of confusing
but not a giant sequoia. Stand next would you go into? people with definitions, here’s how
to your chosen thing and — with Would you point out that I’d define right ascension to a new-
your friend — pace out 10 steps astronomers usually measure right bie now: It’s a coordinate system
and turn around. Gauge the appar- ascension in hours, minutes, and just like longitude on Earth, but it
ent size of the object. Then pace out seconds? That it’s one of the two moves with the stars.
five steps toward the object and spherical coordinates used to mea- In the early 1960s, American
examine it again. Boom! You’ve just sure the positions of objects in the social scientist and Nobel laureate
doubled the magnification. sky? That John Flamsteed, the Herbert Alexander Simon wrote
Astronomer Royal of England, first that something is simple or complex
Jargon used this coordinate in a star cata- depending on the way we choose to
Newcomers to our hobby aren’t log? That 0 hours marks the spot of describe it. As a group of hobbyists
alone in dealing with a huge num- the vernal equinox? That preces- who desire to grow our field of
ber of strange terms. A person sion causes the right ascensions of interest, let’s err on the side of sim-
could be listening to an economist celestial objects to change in a plicity. And we’ll all have lots of
talk about game theory, a computer roughly 26,000-year cycle? chances quite soon. The astronomi-
specialist praise the latest GUI, or Merriam-Webster defines jargon cal event of our lives — the great
an amateur astronomer detail his several ways. My two favorites are American total solar eclipse on
mirror’s Strehl ratio. In all these “confused unintelligible language” August 21, 2017 — just took place. If
examples, a better than average and “obscure and often pretentious you weren’t barraged with questions
chance exists that a word or two language marked by circumlocu- about it, it’s probably because people
will slip by undefined. tions and long words.” Here at the don’t know you’re an amateur
Try this: Pretend you’re talking magazine, we try to avoid jargon, astronomer. Tell ’em.

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