July Perigee Moon #2

   The Moon reaches perigee, (minimum distance from Earth), this month on Wednesday July 27th. At that time the Moon will more or less be at a distance of 28.98 Earth diameters (369,662 km or 229,697 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 27th the thin 23-day old last quarter Moon rises around midnight local time, and is west from the open star cluster the Pleiades.
   
   
   
   
   
   
   *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?”

   
   
   

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.

Moon Passes Uranus


   In the hour or so before sunrise look southeast for the 22-day old 3rd quarter Moon to be within about 3o from Uranus. Both will fit within the field of view of binoculars however the big difference in apparent magnitudes (Moon: -12.0; Uranus: 6.0) and the closeness of the two will make seeing Uranus nearly impossible.

Moon Descends on Neptune

apr5-descending-node
   Saturday July 23rd 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 19-day old waning gibbous Moon rises around midnight local time and is over the southwest horizon at sunrise. The Moon will be close to the the outermost planet Neptune, an event that happens regularly throughout the year due to Neptune’s proximity to the ecliptic and the Moon’s orbit which keeps it near or crossing the ecliptic. Neptune at 8th magnitude will be outshone by the much brighter reflected sunlight from the Moon at nearly -13th magnitude. Between the Moon and Neptune is the 3rd magnitude star Lambda Aquarii in the constellation Aquarius the Water Bearer.

   
   
   
   

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.

Sun Not In Leo


   According to the pseudoscience of astrology, Friday July 22nd the sun will be entering the constellation of Leo the Lion. In fact the Sun is still within the boundaries of the constellation Cancer the Crab, having just entered that region two days ago.
   The difference between the two locations of the Sun, the correct astronomical vs. the incorrect astrological, is due to the effects of precession, or more specifically, the precession of the Earth’s axis. The Earth wobbles on its axis like a spinning top does as the top slows down. So, in approximately 26,000 years the Earth will have spun, or wobbled one time. This is a repetitive cycle and over the course of one precession cycle the poles of the Earth trace out a circle against the background stars over their respective pole. any star on or nearest to this precession circle is the pole star. Currently the north pole of the Earth points toward Polaris and within this century, due to precession, will point the closest it will be, and then over time the Earth’s north pole will shift away.
   Another effect of precession has been to cause the celestial grid system to shift moving the original signs of the zodiac by at least one constellation to the west. In other words the Sun is more to the east which in effect means that whatever your zodiacal sign may be according to astrology, you are really the constellation to the west, or before it according to Astronomy.
   Click here to read a little more about precession from a previous blog.
   The Science of Astronomy has its roots in astrology with the origins of astrology beginning several millennia ago possibly by the Babylonians. Regardless of its origins the basis for at least Sun astrology, the popularized version printed in newspapers, is the position of the Sun relative to stars in the background. However we now know that due to the effects of precession the Sun’s position is no longer as it was during the beginnings of astrology.
    The slideshow below shows the sun’s position within Cancer on July 22nd 2016 AD, and then shifts to show the sun in Leo 4,000 years ago on 22 July 2016 BC. Precession has shifted the sun’s position one constellation to the west.

This slideshow requires JavaScript.

   
   
   

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.

Sun Enters Cancer

19july-view-from-earth   Wednesday July 20th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Gemini the Twins and into the constellation of Cancer the Crab. 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 monthly observing information, or here to go to bobs-spaces.

Six Visible Planets Now Visible!


   Over the next few evenings the two inner planets will come within less than a degree from each other and then pass by as each moves eastward away from the Sun along their respective orbits. This animated graphic is set for my local sunset time of 8:41 pm CDT and cycles through each graphic at 1-day intervals starting with Saturday July 16th and ending on the 20th. The graphic also illustrates how low the two inner planets are relative to the position of the Sun at the horizon and how challenging it may be to see them due to local horizon circumstances.
   Not only are the two inner planets visible but stretching across the horizon to the east from Mercury and Venus are 3 more visible planets, Jupiter, Mars, and Saturn, and of course at your feet is the 6th visible planet, Earth. At times like this, with several of the 8 planets above the horizon it is easy to visualize the ecliptic by sort of connecting the dots (planets). The 8 planets all orbit the Sun with orbits that are close to being parallel to the plane of the Earth’s orbit, the ecliptic, with none of the 8 planets having an inclination, tilt, of more than 7o away from the ecliptic.

This slideshow requires JavaScript.


   
   
   

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.

Uranus at West Quadrature-2016

orbital-positions   Saturday July 16th the position of the planet Uranus, with respect to the Earth and the Sun, places this ringed planet at what is called western quadrature. At that orbital position Uranus, and actually any outer planet, is at a 90 degree angle from the Earth as this graphic shows, and the banner graphic at the top of the page shows. Think third quarter Moon as that is a fair comparison of the relative positions of Earth, Sun, and Uranus.

    At western quadrature Uranus leads the Sun across the sky from east to west as the Earth is rotating, meaning that Uranus rises before the Sun and also sets before the Sun.

   This is a short video clip from a much longer video that I made as part of a live musical performance called “Orbit” at the Gottleib Planetarium in Kansas City Missouri during May 2011.

   
   
   

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.