June Perigee Moon

   Our Moon reaches perigee, (closest distance from Earth), for this orbit on Thursday June 14th. At that time the Moon will be at a distance of 28.18 Earth diameters (359,500 km or 223,383 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*

   Thursday evening May 14th, shortly after sunset local time (8:26 CDT), look toward the western horizon for a conjunction between a thin 1.25-day young waxing crescent Moon and the innermost planet Mercury. The two will be about 2-3o apart but very low over the western horizon.

   *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.


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Venus and the Twins


   Over the next few evenings, June 7th to 10th, the inner planet Venus will pass the star Pollux, marking the head of one of the Gemini Twins. Pollux is on the left side as we view the ‘Twins’ face-on. This animated graphic is set for 10 pm CDT and shows the daily movement of Venus toward the east, combined with the daily motion of the stars toward the west as the Earth revolves around the Sun.


   The separation between Venus and Pollux will vary from about 4.5o to about 5.5o allowing at least these two to fit within a binocular field of view.

   
   
   

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

June Moon at Descending Node and Conjunction with Mars


   Sunday June 3rd 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 morning of the node crossing the 19-day old waning gibbous Moon will be over the south-southeastern horizon about an hour before the Sun rises local time. The Moon will also be about 3o from the ‘red planet’ Mars. Off to the west is the planet Saturn nestled within the glow of the eastern side of the Milky Way.

   Depending on how dark the sky is where you are viewing from and how early you want to go outside, the area around Saturn is rich with some of the best deep-sky objects visible with binoculars. So the earlier you are out, before moonrise, the darker the sky will appear making it easier to see some of Messier Objects in the area near Saturn.

   
   
   
   
   

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.

June Moon At Apogee

   Our Moon reaches apogee, (greatest distance from Earth), on Saturday June 2nd. At that time the Moon will more or less be at a distance of 31.77 Earth diameters (405,300 km or 251,842 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 apogee the 18-day old waning gibbous Moon will be over the southern horizon and beteen the planets Saturn and Mars.

*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 in Conjunction with Saturn



   Thursday May 31st and Friday June 1st the just past full Moon, a waning gibbous Moon, will pass by one of the four the ringed planets, the planet Saturn. Both rise after sunset local time and will be over the western horizon before sunrise the following morning.

   
   
   
   
   
   

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

It’s the Autumn Equinox on Mars

   Tuesday May 22nd is the autumnal equinox on the planet Mars as the planet transitions from summer during its 684 Earth day orbit around the Sun.
   Seasons on Mars are marked by the planet’s heliocentric longitude coordinates using the position of Mars along its orbit around the Sun. At the Martian spring equinox Mars is at 0o longitude.
   Each seasonal start/ending point is 90 degrees apart, but because of an elliptical-shaped orbit each Martian season is of varying lengths. Mars is at its greatest distance from the Sun, aphelion, before it reaches the Martian summer solstice when Mars is at 70o longitude. Perihelion, its closest to the Sun, is when Mars is at 250o longitude.
   Eccentricity of Mars and Earth for comparison.
Mars: 0.0934 – Earth: 0.0167

   I’m not exactly sure why this particular date is used but by international agreement astronomers have selected 11 April, 1955 as 0 degrees for year 1 of this Martian calendar. What this means is that on Tuesday May 22nd, Earth time, it is the start of autumn of year 34 using the aforementioned calendar system.

Year 34
0 degrees — Spring Equinox — May 05 2017
90 degrees — Summer solstice — November 20 2017
180 degrees — Fall Equinox — May 22 2018
270 degrees — Winter Solstice — October 16 2018

Year 35
0 degrees — Spring Equinox — March 23 2019
90 degrees — Summer solstice — October 08 2019
180 degrees — Fall Equinox — April 08 2020
270 degrees — Winter Solstice — September 02 2020

Year 36
0 degrees — Spring Equinox — February 07 2021
90 degrees — Summer solstice — August 25 2021
180 degrees — Fall Equinox — February 24 2022
270 degrees — Winter Solstice — July 21 2022

   Learn a little (or a lot) more about the exploration of Mars at the NASA Journey to Mars web site.

   Learn a little (or a lot) more about Mars at the NASA/JPL Mars Curiosity mission web site.
   Or read about the InSight mission currently on its way to Mars.

   
   
   

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 Really in Gemini

  According to the pseudoscience of astrology the Sun enters the constellation of the Gemini Twins on Monday May 21st. When in fact the actual position of the Sun on this date is still within the boundary of the constellation of Taurus the Bull, as this graphic and the banner graphic show.

   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.