THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
70 Falmouth Street Portland, Maine 04103
43.6667° N, 70.2667° W
Founded January 1970
"Made from the best stuff off Earth."
THE DAILY ASTRONOMER
Tuesday, January 12, 2016
A Plethora of Petite Pandoras
Biologists have, rather foolishly, abandoned the notion of spontaneous
generation: the concept that inanimate matter that can spontaneously
generate living beings. For instance, the blend of rain water and
dirt, apart from making mud, was once believed to have also spawned
worms. Some scientists based this conclusion on their observation
that worms seemed to proliferate after a rain storm. Subsequent
research revealed that worms require moisture for respiration and
therefore tend to remain in moist soil during dry conditions, but are
able to ascend to the watery surface after a recent rain fall.
Though modern scientists assert that inanimate matter can't procreate,
one must recognize that biologists have not fully studied the mating
habits of neglected paperwork. They haven't observed how the
unprocessed invoices and incomplete spreadsheet print outs, when left
alone on a darkened desk, will recognize each other as soul mates and
in their coupling sire a proliferation of other paperwork that, if
neglected, will, yield to the primal temptation and engender a litter
of progeny that...and, well, enough said.
The same occurs with the question slips that we stuffed inside
Pandora's Jar. Over the last few weeks, these, too, have been left
alone in, of all places, a star dome and now the smattering of
parchment strips has expanded into a swarm. So, today, in an attempt
to stem the flow, we have extracted those questions that require brief
answers and have stuffed them all into one article.
Do not infer from this completely pointless preface that we are
displeased to receive questions. In fact, we enjoy receiving and
answering them immensely. We're merely attempting to explain why
we're offering not just one or two questions in today's DA.
Incidentally, unless one is referring to caustic relatives, four
hardly constitutes a plethora. We chose the word merely for
alliteration.
WILL SIRIUS ALWAYS BE THE BRIGHTEST STAR?
No. Sirius is the brightest night sky star now owing to its close
proximity to us: about 8.6 light years. It is certainly not the
intrinsically brightest star in vicinity. Also, like all the other
stars, Sirius moves and its position relative to the solar system is
always changing. Presently, Sirius is moving toward the solar system
at 5.5 kilometers per second. This decreased distance will enhance
its brightest over time. However, Vega, which is intrinsically
brighter than Sirius, moves toward the solar system presently at 13.4
kilometers per second. Of course, Vega is about 26 light years away
and now appears slightly dimmer than Sirius. However, in about
200,000 years, Vega will appear as bright as Sirius and then will
become brighter. Even though it will remain more distant than Sirius,
it is a more luminous star and will eventually become the brightest
star in Earth's sky.
DO OTHER PLANETS HAVE AURORA DISPLAYS?
Yes. Aurorae have been observed on Jupiter, Saturn, Uranus,
Neptune, Venus, and Mars as well as on Earth. Astronomers have not
observed aurora on Mercury, nor should we have expected them to, as
Mercury lacks an atmosphere. Aurora occur when charged solar
particles excite the atoms within a planet's atmosphere. When
excited, the electrons within the atoms are elevated to higher energy
states. When these electrons settle down to their original states,
they emit photons. These photons will not only be within the
visible light spectrum, of course. We notice that Jupiter's aurora
displays, for instance, consists of ultra violet photons.
[If you consult the Daily Astronomer web-page, you can see images of
the aurora elsewhere in the solar system:
http://usm.maine.edu/planet/da-7-december-2015 ]
DO WE GET HEAT FROM THE STARS?
Yes, BUT, the heat is so slight as to be negligible. Let's regard
Sirius, for instance. It is the brightest night sky star and
presumably would impart more heat onto Earth than any other star,
apart from the Sun, of course. Scientists have estimated this heat
to be equivalent to that of a candle 3.5 miles from you. Sirius is
giving me as much heat energy as a smoker down on the wharf provides
me every time he ignites his Zippo. Though the stars are immensely
hot, they are also far away. Light and heat energy diminish with
the square of the separation distance. Let's imagine you are
standing three feet from a flame. If you double your distance from
that flame, the heat energy it imparts onto you will be reduced to one
fourth of the original amount. When one is dealing with distances
in light years, the reduction is highly significant.
CAN ASTRONOMERS EVER DIRECTLY SEE EXO PLANETS?
Yes they can and have directly "imaged" exo planets, those planets in
orbit around other stars. Capturing direct images proves
exceedingly difficult because a planet's reflected light is often
overwhelmed by the star's light. However, if the star is
sufficiently large and reflects a lot of its incidental light, it can
be resolved as a separate image. Also, if a planet radiates copious
heat energy, it will produce a bright infra red image. As long ago
as 2004, astronomers captured a separate image of 2M1207b, a planet
revolving around a brown dwarf. The Hubble Space Telescope imaged
an exo-planet around the star Fomalhaut in 2008. Other exo planets
have been directly imaged since this discovery. Astronomers are also
now using coronagraphs, which are telescope attachments designed to
block a star's light. This occultation enables astronomers to
capture separate image of the star's attendant bodies, such as
planets.
Written by Edward Gleason
Manager, Southworth Planetarium
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