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

                " A blonde and a lawyer are seated next to each other on a flight from LA to NY. The lawyer asks if she would like to play a fun game? The blonde, tired, just wants to take a nap, politely declines and rolls over to the window to catch a few winks. The lawyer persists and explains that the game is easy and a lot of fun. He explains, "I ask you a question, and if you don't know the answer, you pay me $5.00, and vice versa. " Again, she declines and tries to get some sleep. The lawyer, now agitated, says, "Okay, if you don't know the answer you pay me $5.00, and if I don't know the answer, I will pay you $500.00." This catches the blonde's attention and, figuring there will be no end to this torment unless she plays, agrees to the game. The lawyer asks the first question. "What's the distance from the earth to the moon?" The blonde doesn't say a word, reaches into her purse, pulls out a $5.00 bill and hands it to the lawyer. "Okay" says the lawyer, "your turn." She asks the lawyer, "What goes up a hill with three legs and comes down with four legs?" The lawyer, puzzled, takes out his laptop computer and searches all his references, no answer. He taps into the air phone with his modem and searches the net and the library of congress, no answer. Frustrated, he sends e-mails to all his friends and coworkers, to no avail. After an hour, he wakes the blonde, and hands her $500.00. The blonde says, "Thank you," and turns back to get some more sleep. The lawyer, who is more than a little miffed, wakes the blonde and asks, "Well, what's the answer?" Without a word, the blonde reaches into her purse, hands the lawyer $5.00, and goes back to sleep. Moral:  Blondes are brilliant!"

                    -Stolen from a joke web-site

THE DAILY ASTRONOMER

Tuesday, July 5, 2016

July 2016 Night Sky Calendar

We're sending Tuesday's DA early simply because one hardly benefits from reading about an important celestial event that happened yesterday.     Fortunately, the first noteworthy* astronomical event occurs this month on the 4th, which allowed us the weekend to prepare this calendar.

MONDAY, JULY 4:  NEW MOON

Beginning of lunation cycle 1157.

MONDAY, JULY 4: EARTH AT APHELION

There is nothing much to see here, unless you're measuring the Sun's "semi-diameter," and notice that it has reached its minimum value for the year.    Today, Earth has reached aphelion, the most distant point in its orbit.    This distance is approximately 94.5 million miles, compared to its average distance of 93 million miles.  This increased distance has a negligible effect on weather.  However, summer is the longest season because Earth is farthest in its orbit and therefore moving more slowly around the Sun than it does at other times of year.   The seasonal durations are as follows:   Winter    88.9 days; Spring     92.8 days; Summer 93.6 days and Autumn  89.85 days. 

TUESDAY, JULY 5:   MOON 5.1 DEGREES SOUTH OF VENUS

Consider this one to be an "academic event," meaning that we won't see it, but we still wanted to mention it.     Venus and the very young crescent moon lurk quite low in the western evening sky.   We've included this event because we've dearly missed Venus and it will soon return to our evening sky.      The planet's close approach to the waxing crescent moon heralds its imminent reemergence into the firmament. 

THURSDAY, JULY 7:  MERCURY AT SUPERIOR CONJUNCTION

What a beautiful time to review some definitions.

"Inferior conjunction" occurs when a planet moves between the Sun and Earth.  Only the inferior planets -Mercury and Venus-  can ever be in inferior conjunction

"Superior conjunction" occurs when a planet moves to the far side of the Sun relative to Earth.  All the other planets, including Mercury and Venus, can be in superior conjunction.   This statement might initially seem counter intuitive, but just imagine the solar system from "above."  One can then easily imagine the Sun positioned between Mercury and Earth or between Earth and Venus. 

We remember that on May 9th, Mercury was at inferior conjunction around the same time it was at a node.   A "node" is the intersection point between two planetary orbits.  We therefore saw a "transit," the direct passage of Mercury across the Sun's façade.    Mercury's orbit is inclined relative to Earth's by seven degrees.  Consequently, most of the time Mercury is at inferior conjunction, it will be "north" or "south" of the Sun and  no transit will occur.    We have to wait until November 2019 for the next Mercurian transit

THURSDAY, JULY 7:  PLUTO AT OPPOSITION

Yet another academic event!   Pluto is about 1600 times fainter than the dimmest naked eye stars.    Unless one observes the sky through a powerful telescope, one will not be able to see this distant PLANET.    However, Pluto is hardly ever mentioned in these night sky calendars and we wanted to tell you that today Earth passes between Pluto and the Sun.

SATURDAY, JULY 9:   MOON 0.81 DEGREES SSW OF JUPITER  (GOLD EVENT!!!)

Although Jupiter remains a prominent evening sky object, it will vanish in late summer, only to return to the early morning mid autumn skies.   Now that we're watching Jupiter's final act, we see it close to the crescent moon.   Interesting note: the moon will appear to occult (block) Jupiter from some regions of Antarctica.

TUESDAY, JULY 12:  FIRST QUARTER MOON

THURSDAY, JULY 14:   MOON 7.6 DEGREES NNE OF MARS (SILVER EVENT!!)

Though not quite as brilliant it was in May during its opposition, Mars is still quite bright and will be easy to find tonight as it veers close to the gibbous moon.

SATURDAY, JULY 16: MOON  3.4 DEGREES NORTH OF SATURN (BRONZE EVENT!)

Saturn is dimmer than Mars and Jupiter, but still moderately bright.     Tonight, one will observe the ringed planet poised "under" the gibbous moon.     This appulse presents telescope owners with a splendid opportunity to observe features of both worlds, including the moon craters and Saturn's rings.    Craters are much easier to observe with a telescope and Saturn's rings are only visible in a telescope and binoculars.

TUESDAY, JULY 19:  FULL MOON

We call the July full moon the "thunder moon" or the "hay moon."  Southern Hemisphere observers refer to it, logically, as the "ice moon," because those lucky sods are currently experiencing winter! 

WEDNESDAY, JULY 20: SUN ENTERS CANCER THE CRAB

We often say that the Sun moves through thirteen constellations each year. It does nothing of the sort.  Instead, Earth moves around the Sun and it therefore appears to migrate through thirteen constellations.  We refer to this retinue as the "Zodiac," or "Ecliptic Band."  Today, we see the Sun cross into the Cancer the Crab region after having left Gemini the Twins.  The thirteen "zodiac" constellations are    CANCER THE CRAB; Leo the Lion; Virgo the Maiden; Libra the Scales; Scorpius the Scorpion; Ophiuchus the Serpent Charmer; Sagittarius the Archer; Capricornus the Seagoat; and Aquarius the Water Bearer, Pisces the Fish; Aries the the Ram; Taurus the Bull and Gemini the Twins. The Sun moves into Leo the Lion on August 10th.

MONDAY,  JULY 25:  EQUATION OF TIME REACHES A MINIMUM OF -6.5 MINUTES

This will likely be the last academic event of the month.     Once a day, the Sun appears to cross the "meridian," a line connecting due south and due north.    This crossing, properly known as "upper culmination," doesn't generally happen at noon.     In fact, the Sun reaches upper culmination precisely at noon about four days of the year.    On other days, the Sun will either be just beyond the meridian at noon or will not quite have reached it.  The equation of time, which in this sense means 'correction,' indicates the time difference between civil noon and upper culmination.      Today, the Sun reaches the merdian at 12:06:50 p.m.  After today, the Sun will be closer to the meridian at noon each day and will then be at upper culmination at noon on September 1st, when the equation of time will be zero.  (I have to wonder if this paragraph will be as exciting to readers as it sounded in my head.  If it does, my apologies.)

TUESDAY, JULY 26:  LAST QUARTER MOON

THURSDAY, JULY 28:   MOON 9.1 DEGREES SOUTH OF THE PLEAIDES

It's rather strange, isn't it?  Here we are in depths of summer and the winter stars are now rising in the pre-dawn eastern sky.   This morning, one will find the crescent moon close to the Pleiades Star Cluster, that gorgeous amalgam of stars poised on Taurus the Bull's back.     Some skywatchers will rejoice at the return of winter's stars, which are admittedly brilliant, beautiful and look smashing when looming above crystalline snowscapes.   However, in such sultry weather, these stars seem strangely misplaced.

SATURDAY, JULY 30:  MERCURY 0.30 DEGREES NNE OF REGULUS

The closest appulse of a planet and a first magnitude star.   Regulus is the alpha star within Leo the Lion.   Mercury and Regulus will be only twenty-two degrees from the Sun in the western evening sky.

PLANET WATCH

MERCURY:  [HOST CONSTELLATION:  LEO THE LION]   is gone most of the month.  It returns to the evening sky late in July and will be slightly easier to observe by the last week of the month.  See it close to Regulus on July 30th. (See above)  VERDICT:    Don’t bother searching for Mercury until at least July 21st. See it out in the western evening sky.

VENUS: [HOST CONSTELLATION:  CANCER THE CRAB] has been gone for quite awhile.  It vanished in the morning sky early in April.   Late this month, it finally returns to the evening sky.   VERDICT:  Wait until very late this month or, actually, you could wait until early August to find Venus now that it has finally returned to our sky after a prolonged hiatus.

MARS (PICK PLANET!)   [HOST CONSTELLATIONS  LIBRA THE SCALES/SCORPIUS THE SCORPION] We're giving Mars the coveted crown because it remains bright and it up all evening. Jupiter is slightly brighter, but it doesn’t stay in the evening sky for long.    Saturn received the crown last month.  Mars sets after midnight at month's beginning and by midnight at month's end.  VERDICT:   July 2016 is a perfect month to seek out Mars, a beautiful evening sky beacon.

JUPITER:  [HOST CONSTELLATION: LEO THE LION] The giant planet sets in the early evening.  By August, it will be setting in twilight.    Now that Mars is moving away from Earth, Jupiter is once again the brightest evening sky a planet, a distinction it will lose by late July when Venus returns.   VERDICT:   Find Jupiter when you can. It will vanish by early September, only to return to the morning sky in mid October.    Seek Jupiter in the early evening western sky.

SATURN: [HOST CONSTELLATION:  LIBRA THE SCALES]   The sixth planet is slowly growing dimmer as its distance from Earth increases.  However, Saturn sets after midnight and won't disappear into the dusk until late autumn.   VERDICT:    While you're out admiring Jupiter and Mars, you might as well look eastward to admire Saturn.

PLANETS IN ORDER OF DECREASING BRIGHTNESS

MONTH'S BEGINNING

JUPITER  --   MARS  --    SATURN

MONTH'S END

VENUS --- JUPITER --  MARS -- MERCURY -- SATURN

*The term "noteworthy" is vague.  Some astronomers would assert that each month contains hundreds, if not thousands, of noteworthy events.     Of course, because of space constraints, we have to be somewhat more discriminating.