THE SOUTHWORTH PLANETARIUM
70 Falmouth Street      Portland, Maine 04103
(207) 780-4249      usm.maine.edu/planet
43.6667° N    70.2667° W
Founded January 1970
2022-2023: XXXIII
Sunrise: 7:17 a.m.
Sunset: 5:32 p.m.
Civil twilight ends: 6:02 p.m.
Sun's host constellation: Libra the Scales
Moon phase: Waning Crescent (43% illuminated)
Moonrise: 2:45 p.m.
Moonset: 12:09 a.m. (11/2/2022)
Julian date: 2459885.21
"Just sitting quietly, doing nothing at all, your brain churns through more
information in thirty seconds than the Hubble Space Telescope has processed
in thirty years. A morsel of cortex one cubic millimeter in size -about the
size of a grain of sand- could hold two thousand terabytes of information,
enough to store all the movies ever made, trailers included, or about 1.2
billion copies of this book. Altogether, the human brain is estimated to
hold something on the order of two hundred exabytes of information, roughly
equal to "the entire digital content of today's world," according to *Nature
Neuroscience*. If that is not the most extraordinary thing in the universe,
then we certainly have some wonders to find." - Bill Bryson "The Body: a
Guide for Occupants."



THE DAILY ASTRONOMER
Tuesday, November 1, 2022
November 2022 Night Sky Calendar Part I

*TUESDAY, NOVEMBER 1: FIRST QUARTER MOON*

*TUESDAY, NOVEMBER 1: MOON NEAR SATURN*
The first quarter moon (50% illuminated) appears to glide to the south of
Saturn, that magnificent ringed world that, in our sky, merely resembles a
star, except, of course, that it doesn't twinkle or scintillate. As Saturn
is currently the dimmest of the naked eye planets (magnitude 0.7)* the moon
will help one find it tonight. Just look for the moderately bright "star"
just north of the quarter moon.

*THURSDAY, NOVEMBER 4: MOON NEAR JUPITER (SILVER EVENT!!)*
As Jupiter is the brightest of the naked eye planets -Venus is currently
too close to the Sun to be observed- its coupling with the waxing gibbous
moon (83% illuminated) should make for a lovely celestial sight. Both
worlds will be high in the eastern sky after dark and will set by 3:00 a.m.

*TUESDAY, NOVEMBER 8: TOTAL LUNAR ECLIPSE (PLANTINUM EVENT!!!!)*
This morning, we will see the full moon moving directly into Earth's inner
shadow, called the *umbra*. As this eclipse occurs in the early morning, we
won't be able to observe the entire event. Instead, we'll watch the first
phases. The moon will actually set here during totality. Not only will we
not see the moon move out of the umbra, the entire moon will appear to
vanish in the western sky as the pre-dawn twilight brightens. All the same,
such events are always exciting and well worth the sleep deprivation.
[Note: we're going to offer a more comprehensive article about the lunar
eclipse on Monday, November 7th.] The time-line is below:

*PENUMBRAL ECLIPSE BEGINS * - 3:02:15 a.m.
Nothing to see here. The moon first touches the *penumbra*, the outer part
of Earth's shadow. The resultant brightness diminishment is so slight as to
be unobservable. While those in possession of superhuman eyesight might be
able to notice an obscuration, we mortals would just look upon a full moon
as it, well, always appears.

*PARTIAL ECLIPSE BEGINS - *4:09:12 a.m.
This is what you'll likely want to see: the moon first touches the umbra.
Now, you can observe the curved shadow moving across the bright lunar disc.
During the next hour and seven minutes, the moon will move progressively
deeper into the umbra until it is completely covered.

*TOTAL ECLIPSE BEGINS * - 5:16:39 a.m.
Totality, the time period in which the moon is completely inside the umbra,
begins.

*MAXIMUM ECLIPSE* - 5:59:11 a.m.
The moment when the moon passes through the deepest part of the inner
shadow.

*MOON SET * - 6:32 a.m.
The moon sets from our perspective. Do note, however, that the moon will
likely be difficult to see during most of totality, however, due to its low
position along the western horizon.

We'll include the rest of the timetable for completeness:

*TOTALITY ENDS - *6:41:36 a.m.
The moon starts to leave the umbra

*PARTIAL ECLIPSE ENDS - *7:49:03 a.m.
The moon leaves the umbra. The scarcely visible penumbral eclipse continues

*PENUMBRAL ECLIPSE ENDS - *8:56:09 a.m.
The eclipse ends.

*TUESDAY, NOVEMBER 8: MERCURY AT SUPERIOR CONJUNCTION*
A purely academic event. Mercury moves to the far side of the Sun relative
to Earth and so will not be visible. A planet on the Sun's far side is said
to be in *superior conjunction*. A planet that passes between the Sun and
Earth is said to be in *inferior conjunction*. The graphic below shows the
various configurations and their associated positions. Note that all the
other planets can pass into superior conjunction, but only the inferior
planets -those closer to the Sun than Earth- can ever be in inferior
conjunction.
[image: Super-conjunction.gif]

So, one must wonder:  how often does one experience a total lunar eclipse
at the same time that Mercury passes into superior conjunction on a
mid-term election day?    The world will never know.



*Let's talk about magnitudes for a few minutes. The concept of "magnitude"
is actually quite straightforward. It is the system astronomers use to
measure the brightness
of celestial objects: stars, planets, the Moon, even comets, asteroids and
meteor trails. If it's in the sky and exudes light,
either self-generated or reflected, it has a magnitude value. As we shall
discover, this system is both useful as a categorizing tool and as a means
of discerning stellar distances.

Historians credit the magnitude system's invention to Nicean astronomer
Hipparchus (190 - 120 BCE*) His was the first catalog to include a
six-category scheme indicating stellar brightnesses. He assigned the
brightest stars the designation "magnitude 1." He labeled the faintest
stars visible as "magnitude 6." He consigned the remaining stars to the
four intervening categories based on their relative brightnesses. As each
category was not calibrated to reflect variations within each one,
Hipparchus' scheme was quite imprecise. Yet, it became the foundation on
which the modern magnitude system was based. British astronomer Norman
Robert Pogson (1829 - 1891) formulated the magnitude system astronomers
still use today. He introduced into this system a value known as the
"Pogson ratio," which is 2.512. A star measuring magnitude 1.0 is 2.512
times brighter than a star of magnitude 2 which, itself, is 2.512 times
brighter than a magnitude 3 star. Pogson selected this ratio because it is
the fifth root of 100, so a magnitude 1 star is precisely 100 times
brighter than a magnitude 6 star. Apart from quantifying the system, Pogson
also expanded its parameters to accommodate both the objects that are far
brighter than those stars previously denoted as magnitude 1 and the objects
visible through telescopes. Today, the magnitude system extends from the
Sun (magnitude -26.7) to the faintest celestial objects that the Hubble
Space Telescope has observed (magnitude + 27) As examples, Sirius, the
brightest night sky star, is magnitude -1.46; Venus, at maximum brightness,
is magnitude -5.0.
Presently, Venus' magnitude is -4.0, Jupiter's is -2.2 and Mars' is 1.0. We
can use this information to measure the relative brightnesses of these
planets.
Comparing Venus and Mars is rather simple. The magnitude difference is
exactly 5, so we determine that Venus appears 100 times brighter than Mars.
Comparing Venus with Jupiter or Jupiter with Mars is a bit more involved,
since the magnitude difference is not a convenient whole number.
Let's regard Venus and Jupiter. The magnitude difference is 1.8. To
translate this difference into a comparative brightness ratio, we multiply
1.8 by 0.4 and then raise 10 to the resultant value.

First step => 1.8 x 0.4 = 0.72

Second step => 10 raised to the power of 0.72 = 5.24.     [Here's the
simple notion behind the daunting phrase "raise to the power." The sentence
"10 raised to the power of 2" means 10 multiplied by itself. 10 x 10 = 100.
"10 raised to the power of 3" means 10 x 10 x 10 = 1000. When written out
in proper mathematical notation, one would see 10 with a superscript 2 or 3
at the upper right of the 10.     So, 3 raised to the power of 3 is 3 x 3 x
3 = 27.]

So, Venus is slightly more than five times brighter than Jupiter.

Let's follow the same procedure for Jupiter and Mars:

Magnitude difference is 1.0 - (-2.2) = 3.2

First step => 3.2 x 0.4 = 1.28

Second step => 10 raised to the power of 1.28 = 19.05

Jupiter is slightly more than 19 times brighter than Mars.

Comparing brightness is merely one application of magnitude.
Another application involves stellar distance calculation using an equation
called the "Distance Modulus."

Before we introduce this modulus, we need to explain the difference between
"apparent magnitude," which measures how bright an object appears to
"absolute magnitude," which pertains to an object's intrinsic (true)
brightness.

Apparent magnitude, denoted by m, is somewhat simple to measure. One looks
at an object and measures how bright it appears in the sky. The magnitude value
for Sirius (-1.46) is its apparent brightness.

A celestial object's absolute magnitude, denoted by M, is equal to the
apparent magnitude the object would have if it were 10 parsecs from Earth.
(A par-sec is 3.26 light years.) If Sirius were 10 parsecs from Earth, its
apparent magnitude would be 1.43.

Now, let's look at those two values. Sirius' apparent magnitude (m) is
-1.46, but its absolute magnitude (M) is 1.43.
We know from the first section, that the lower the number, the brighter the
object. So, Sirius is actually brighter than it would be if it were 10
parsecs (32.6 light years) away. What can we conclude? Elementary. Sirius
must be closer than 10 parsecs. If its absolute magnitude and apparent
magnitude were the same, Sirius would be exactly 10 parsecs away. If the
absolute magnitude value was lower than the apparent magnitude, Sirius
would be farther away than 10 parsecs.
These paragraphs can be tedious, so let's make a chart.

m = M the object is 10 parsecs away

m < M the object is less than 10 parsecs away

m > M the object is more than 10 parsecs away.


Antares, for instance, has an apparent magnitude of 0.95, but an absolute
magnitude of -5.4
m = 0.95; M = -5.4. We know that Antares is more than 10 parsecs away!

How far?

Well, to answer that question, we need to finally unveil the famous
"distance modulus."

The distance modulus' conventional form is, to many students, a miracle of
discouragement:

m - M = -5 + 5log(d).
(m is apparent magnitude; M is absolute magnitude; and d is the distance
expressed
in parsecs.)

Well, let's pretend that nobody likes the form of this equation because
logarithms are an antiquated pain in the posterior.
So, we're going to make it simpler.

Let the value of m - M = X; multiply X by 0.2; Add 1 to that value; raised
10 to the result.

This is a good time for an example.

ANTARES:

Step 1) m = 0.95; M = -5.4
m - M = 6.35 = X

Step 2) 6.35 x 0.2 = 1.27

Step 3) 1.27 + 1 = 2.27

Step 4) 10 raised to the power of 2.27 = 186.2 parsecs = 607 light years.

So, let's try Sirius:

SIRIUS
Step 1) m = -1.46; M = 1.43

m - M = -2.89 = X

Step 2) -2.89 x 0.2 = -0.578

Step 3) -0.578 + 1 = 0.422

Step 4) 10 raised to the power of 0.422 = 2.64 parsecs = 8.6 light years

Thus, we can see how powerful the magnitude system can be in terms of
comparing brightness and in determining stellar distances. When Hipparchus
devised the magnitude scheme, his aim was simple categorization, without
thought to other applications. We must understand that Hipparchus had no
notion of stellar distances. That the system he devised would prove useful
in endeavors he never even considered is not unique to him, of course.
Scientific history is replete with such examples. It's likely that the
scientific future will be similarly blessed. Trouble arises when one finds
a number like 0.72 as the superscript number. "10 raised to the power of
0.72" is not nearly as easy to solve. Fortunately, such computations are
child's play for scientific calculators. (refer to manual, since not all
calculators have the same procedures.) After using our scientific
calculator, we find that 10 raised to 0.72 is 5.24. (The actual result
shown on the calculator display is 5.24 followed by an endless parade of
numbers that one can cheerfully ignore.)


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