July Moon at Perigee

   The Moon reaches perigee, (minimum distance from Earth), this month on Friday July 1st. At that time the Moon will more or less be at a distance of 28.69 Earth diameters (365,983 km or 227,411 miles) from the Earth.
   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*


On the morning of the 1st the thin 26.5-day old waning crescent Moon rises a couple of hours before sunrise. The Moon forms the west pointing corner of a celestial triangle with the base formed by the open star clusters the Pleiades and the Hyades.
   
   
   
   
   
   
   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars Moves Forward

   Thursday June 30th Mars ends its apparent westward motion (retrograde motion) relative to the stars in the background and resumes its eastward or direct motion. The location of mars for this particular retrograde has the ‘Red Planet’ near a reddish star with a name suggestive of how similar it appears to Mars. This is the star Antares, the heart of Scorpius the Scorpion.
   Antares could be thought to literally translate to ‘anti-Ares’ suggesting that this reddish celestial object should not be confused with Ares, the Greek god of War. Many stars have several names originating several centuries ago and in different languages however many of the translations have Antares meaning ‘equal of Mars’.
   Right now Mars is just past its greatest apparent magnitude, its brightest. This typically happens at around Mars opposition, but Mars is even brighter if its opposition is around the time of its perihelion and the time when Earth is at aphelion.
   Mars is now again moving toward the east and it will gradually move closer to Antares coming within about 1o from Antares on August 24th. However the Earth is also revolving around the Sun so at the same time that Mars is closing in on Antares that part of the sky will be moving further west and setting earlier.

   This year Mars and Antares will still be above the horizon during August and by then local time for sunset will also be earlier.

   
   
   
   
   
   
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.net.

June Moon at Descending Node

apr5-descending-node
   Sunday June 26th the waning gibbous Moon will be crossing the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.
   
   
   
   


   On the day of the node crossing the 21-day old waning gibbous Moon rises shortly after midnight local time and is over the southern horizon at sunrise.

   
   
   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Our Moon and Neptune

   Between Saturday June 25th and Sunday June 26th the waning gibbous Moon will pass close by the outermost of the 8 known planets, Neptune. Depending on your longitude you may see an occultation of Neptune by the Moon. From my location of about 94o west the Moon will pass by Neptune coming as close as around 5o as this graphic shows.
click on animated graphic to see it larger   However observers viewing from the western side of Europe will either see the occultation or see a very close conjunction between the Moon, the star Lambda Aquarii, and Neptune.

25 mm eyepiece   Neptune has an apparent magnitude of nearly 8.0 making it not visible to the naked eye, but certainly within the reach of even moderate sized telescopes.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Sun Does Enter Gemini

   Tuesday June 21st the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Taurus the Bull and into the constellation of The Gemini Twins. This is the true or actual position of the Sun as opposed to the pseudoscience of astrology which usually has the astrological Sun one constellation ahead or east from the Astronomical Sun’s position.

   Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.
   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

June Solstice 2016

21june-ecliptic   Northern hemisphere spring comes to an end and its summer begins on Monday June 20th at 22:34 UT (5:34 pm CDT) when the Sun ‘reaches’ the celestial coordinates of 23.5o north declination and 6 hours right ascension. With respect to the Earth’s surface the Sun is described as over the Tropic of Cancer, 23.5o, north latitude of the Earth’s equator. At this same time the Sun is still within the boundaries of the constellation Taurus the Bull – but just barely. Interestingly about 8 hours later, June 21st at 8 UT (3 am CDT) the Sun ‘will move’ into the region of Gemini as it crosses the boundary between Gemini and Taurus.
   According to the pseudoscience of astrology the Sun, at this date, would be entering the astrological sign of Cancer the Crab.
Just had to include this!!   We know that it is the Earth’s orbital motion around the Sun that causes the sun’s apparent eastward motion among the stars in the background. This is how the Sun ‘reaches’ a celestial coordinate, how it ‘crosses’ the boundaries between constellations, or how it is ‘in’ a constellation.
   With respect to the southern hemisphere this is the end of their summer and start of their fall season. So thinking globally my preference has been to use the name of the month to designate the season change. Hence the use of the term June Solstice rather than summer solstice.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

June Apogee Moon

   Our Moon reaches apogee, (greatest distance from Earth), on Wednesday June 15th. At that time the Moon will more or less be at a distance of 31.75 Earth diameters (405,024 km or 251,670 miles) from the Earth.
   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   The 11-day old waxing gibbous Moon rises a few hours before sunset local time and is east from the blue-white star Spica in Virgo the Maiden. Down to the left from the Moon is Mars, the star Antares, and Saturn.

   
   
   

Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Follow the Moon

   Over the next several days the Moon, as it waxes toward full phase, will follow the ecliptic as it passes by some of its solar system colleagues. Starting on the 15th, a few degrees east from the blue-white star Spica in Virgo the Harvest Maiden, the waxing gibbous Moon will then pass a few degrees from Mars on the 16th and 17th. Then on the 18th the nearly full Moon will be about 3o from Saturn, and that night ending this month’s lunar sweep along the ecliptic and bright planets.
   This animated graphic shows an 'atlas' view of the area along the ecliptic and the the Moon's daily path from June 15th to the 20th. The celestial equator is the curved red line and the ecliptic is the green line.
   There are two distinct motions, and one subtle motion shown in this animation.

    -Planets are in motion with Saturn and Mars on the move with Mars moving toward the west as it retrogrades. On a day to day basis the subtle shift in the position of Saturn and Mars each day is relatively small. Saturn moves 0.033o each day (360o/10,755 Earth days), and Mars each day moves 0.52o (360o/687 Earth days) .
    -The Moon orbits from west to east so each day at the same time the Moon is further to the east, or rises (sets) later.
    -The daily shift in the sky from east to west due to the Earth’s revolution around the Sun. The sky shifts about 1 degree each day or celestial objects, like stars, rise (and set) about 4 minutes earlier each day.

   The graphics below are set for 10 pm CDT on the dates indicated.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Neptune Takes A Break

neptune-retrograde-ani   Tuesday June 14th the outermost of the 8 planets, Neptune, pauses its regular eastward direct motion around the Sun and for the next several months will appear to be moving westward, in retrograde motion, across the constellation Aquarius the Water Bearer. Neptune’s retrograde motion ends on November 20th with Neptune resuming its eastward direct motion.

   Retrograde motion is an apparent motion that the outer planets, relative to the Earth, have. It is an apparent motion that looks as if the outer planet stops it normal direct motion to the east and reverses direction to the west. After a period of time the apparent westward motion ends and the planet resumes its normal orbital path to the east. Retrograde motion happens as the faster moving Earth catches up with and then passes by the outer planet. It is during this time that the backward apparent motion happens.

   The two inner planets also have retrograde motion but it is a result of their orbit around the Sun and not the Earth passing them by. For approximately one-half of their orbit they move east, from western elongation through superior conjunction to eastern elongation. Then at eastern elongation the inner planet starts moving westward through inferior conjunction to western elongation.

   Read a little more about retrograde motion in my February 2012 Scope on the Skies column, drawkcab planets, in Science Scope Magazine.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars and Saturn at Heliocentric Conjunction

   The planets Mars and Saturn are both just recently past the time of their respective opposition to the Earth; Mars on May 22nd, and Saturn June 3rd. When the two dates are close then both planets will at some point be at the same heliocentric longitude or at heliocentric conjunction. That will be on Monday June 13th.

   While they may share nearly identical heliocentric longitude coordinates they do not have the same right ascension with Saturn about 1 hour of R.A. east from Mars. Both Mars and Saturn are very visible over the southern horizon a couple of hours after sunset. The color of Mars contrasts nicely with the reddish star Antares in the Scorpius the Scorpion.

   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.