THE SOUTHWORTH PLANETARIUM 207-780-4249   www.usm.maine.edu/planet
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 70.2667° W  Altitude:  10 feet below sea level Founded January 1970 Julian
Date:  2459379.18
2020-2021: CXLV
              "Crazy Ed's astronomy shop"

THE DAILY ASTRONOMER
Monday, June 14, 2021
June 2021 Night Sky Calendar Part III

Well, finally....after the partial solar eclipse and inconvenient illness,
we finally post the last part of the Night Sky Calendar.   If our return
annoys you,  be not afraid.  Due to the crunch of summer preparations, the
DA has to go on a two week hiatus after today.  It will return on July
1st.   However, we're here now to complete the monthly sky calendar.
Happily,we'll begin with the golden event we've all been so eagerly
anticipating.


*SUNDAY, JUNE 20:  SUMMER SOLSTICE (GOLD EVENT!!!)*

At 11:31 p.m. on Sunday, June 20th, astronomical summer will begin in the
northern hemisphere. Before the Bacchanal frenzy begins, we'll devote some
time to understanding the mechanisms behind this miracle.        We have
seasons because Earth is tilted relative to the plane of its orbit.    This
tilt, called the "obliquity," measures about 23.5 degrees.   As Earth
revolves around the Sun, the pole orientation relative to the Sun
continually changes.




*Earth's tilted orbit.     As Earth revolves around the Sun. the pole
orientation constantly changes.   On the summer (June) solstice, the north
pole is aligned as close to the Sun as possible.  On the winter (December)
solstice, the south pole is pointed as close to the Sun as possible.
 Summer begins in the northern hemisphere on the June solstice.  Image:
 Earthsky.org*

Throughout the year, a northern hemisphere observer will notice the Sun's
altitude changing from season to season.    On the vernal (March) and
autumnal (September) equinox, the Sun rises due east and sets due west.
In the spring and summer, the Sun rises north of east and sets north of
west.     On the summer solstice, the Sun rises as far north of east and
sets as far north of west as possible.   In the autumn and winter, the Sun
rises south of east and sets south of west.   On the winter solstice, the
Sun rises as far south and sets as far south as possible.
*The Sun's changing altitude throughout the year.      As Earth's pole
alignment changes throughout the year, the Sun's altitude varies: from a
minimum position on the winter (December) solstice to a maximum altitude on
the summer (June) solstice.     The Sun's altitude oscillates between these
two extremes during the year.     The winter solstice is also known as
"Midwinter," and the summer solstice as "Midsummer."   Image:  Earthsky.org*

The Sun's altitude directly relates to its time above our horizon.  The
higher the altitude, the greater the path between horizons.  As Earth's
speed is constant along any line of latitude -fastest at the equator and
progressively slower with increasing distance from the equator- the Sun
will remain above the horizon for a longer period of time in the summer
than the winter.   Summer is warmer than winter because the Sun's angle is
higher and it heats the ground more efficiently.   The rising heat from the
surface warms the air above it.

Even though the Sun's altitude will now start decreasing, our weather will
continue to become warmer over the next couple of months.

*WEDNESDAY, JUNE 23: MOON NEAR ANTARES*
Let's review the list of the four first-magnitude stars located quite close
to ecliptic, the Sun's annual path through the sky:


   - Aldebaran (Taurus)
   - Antares (Scorpius)
   - Regulus (Leo)
   - Spica (Virgo)

The moon and planets can move close to or in front of the moon and rarely
planets, as well.*'  Although the moon won't occult -move in front of-
Antares tonight, it will appear to move close to it.    The advantage of
these bright star/moon appulses is that one can observe how the moon's
position changes relative to the bright star.   This position shifts half a
degree each hour.

[image: skychart.ashx.png]

*THURSDAY, JUNE 24:  FULL MOON*
June's full moon names are some of the loveliest of them all:   Rose moon,
Mead moon, Hot weather moon, Strawberry moon and, of course, the all famous
Honey moon, the term referring to the blissful beginning of marriage or
other similarly adventurous enterprise.

*SUNDAY, JUNE 27:   BRIGHT INTERNATIONAL SPACE STATION FLY OVER*
The International Space Station is now visible again, albeit in the early
morning!    On June 27th, we will see the ISS swoop through the pre-dawn
skies and attain a brightness of magnitude -3.1, making it brighter than
Jupiter!  See the details below, courtesy of Heavens-Above.com

Chart size (500 - 1600)





Event Time Altitude

Brightness
Exits shadow 04:25:16 7°

-1.3
Reaches altitude 10° 04:25:46 10°

-1.6
Maximum altitude 04:29:00 45°

-3.1
Drops below altitude 10° 04:32:14 10°

0.6
Sets 04:34:23 0°

2.3


*SUNDAY, JUNE 27:  MOON NEAR SATURN*
See the waning gibbous moon (89% illuminated) appear to move close to
Saturn tonight.   Both bodies will rise just before midnight and remain
visible for the rest of the night.
[image: skychart.ashx1.png]


*MONDAY, JUNE 28:  MOON NEAR JUPITER*
If you missed the moon-Saturn appulse last night, you can see the
moon-Jupiter appulse tonight.  Both the waning gibbous moon (80%
illuminated) and Jupiter will rise just after midnight.


PLANET WATCH

*MERCURY*

*[Host constellation(s)  -  Taurus (June 1); Taurus (June 30)]*
The first world vanished into the dusk at the beginning of June and moved
into inferior solar conjunction on June 10th.   Toward the end of June,
Mercury will emerge in the pre-dawn sky, but shall remain low on the
eastern horizon.   VERDICT:  Difficult month for Mercury.   Best to seek
out at month's end.

*VENUS (PICK PLANET!)*

*[Host constellation(s) - Taurus (June 1); Cancer (June 30)]*
Of course Venus is the pick planet.  As always, it outshines all the other
planets and is currently in the western evening sky.    Our sister world
sets by 9:30 p.m. on June 1st and just before 10 p.m. on June 30th.
VERDICT:  Easy planet!  Venture outside soon after sunset and you'll see
Venus shining like an incandescent torch in the west.

*MARS*

*[Host constellation(s) - Gemini (June 1); Cancer (June 30)]*
Though not particularly bright, Mars does remain in the western evening sky
until just after 10 p.m this month.   VERDICT:   Go out and find Mars while
you can.   The fourth planet will be getting lower in the western sky
throughout the summer as it approaches its October 8, 2021 superior
conjunction.

*JUPITER *
*[Host constellations(s) - Aquarius (June 1); Aquarius (June 30)]*
Jupiter is due to move into the evening sky soon.   For now, it rises in
the early morning.  The giant planet and its companion Saturn are both
morning sky beacons.   Distinguishing between them should be simple,
however, as Jupiter is nearly 14 times brighter than Saturn.  VERDICT:  If
you're up and out before sunrise, seek out Jupiter!   It won't disappoint.

*SATURN*
*[Host constellation(s)  - Capricornus (June 1); Capricornus (June 30)]*
Saturn's ascent heralds Jupiter's imminent emergence.    The ringed world
rises just before midnight, making it an evening sky object.  See it in the
eastern sky anytime around or after midnight.  Jupiter follows in less than
an hour.      VERDICT:   Though not nearly as bright as Jupiter, Saturn
remains an moderately easy planet to observe if you're out before sunrise.

*The next planetary occultation of a bright star occurs when Venus occults
Regulus on October 1, 2044.

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