November Moon at Apogee – And the Ecliptic

click on graphic to see it larger   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Thursday November 26th. For this apogee the 12-day old waxing gibbous Moon will be at a distance of 31.82 Earth diameters, 252,211 miles (405,894 km) from the Earth.

   On the date of the apogee the 12-day old waxing gibbous Moon will be about 12o to the east from the planet Mars. The Moon will also be about 11o west from the outer planet Uranus. Currently Uranus has an apparent magnitude of around 5.7 meaning that it could be seen with the unaided in dark enough skies, or with telescopes and even binoculars – as long as the Moon is not in that part of the sky.

   Along the Ecliptic
   You may notice the arrangement of the planets spread across the horizon as shown in the graphic. Many objects in our solar system orbit the Sun in a path that is somewhat parallel with the Earth’s orbit, the ecliptic. All of the orbits are tilted or inclined away from the ecliptic however the 8 classical planets all have orbits that are inclined less than 7o from the ecliptic. Dwarf planets, asteroids, comets, for example, have orbital inclinations greater than 7o.
   The ecliptic also defines the Sun’s apparent path against the background of stars throughout the year. The planets are also in motion as they orbit the Sun as the video below illustrates.
   Take a short cruise along the ecliptic with the Sun!


   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)
   
   
   
   

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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the Moon and the Beehive Cluster

   During the early morning hours of November 7th and 8th our Moon, as it wanes from gibbous to last quarter, will be passing by M-44, an open star cluster. M-44 is also known as the Beehive Cluster, and is located within the constellation Cancer the Crab.

   
   
   

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.


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Moon Faces Off With Taurus

   Monday evening November 2nd the 17-day old waning gibbous Moon will be alongside the open star cluster the Hyades, a v-shaped group of stars making up the face of Taurus the Bull. The ‘angry eye’ of the Bull, the reddish star Aldebaran, is about 2-3o from the Moon.

   Look for Mars off to the west from the Moon, and Jupiter and Saturn further west over the southwestern horizon.

   
   
   

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.


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October Moon at Apogee #2

   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Friday October 30th. For this apogee the 14-day old waxing gibbous Moon will be at a distance of 31.86 Earth diameters, 252,525 miles (406,400 km) from the Earth.

   On the date of the apogee the 14-day old waxing gibbous Moon will be 13-14o from the planet Mars. The Moon will also be about 11o west from the outer planet Uranus, and about 11o east from Dwarf Planet Eris.


   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)
   
   
   
   

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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Moon – Mars Conjunction

   Over the next two evenings the 12-13 day old waxing gibbous Moon will pass by the ‘Red Planet’ Mars coming within about 7-8o on Wednesday October 28th and within about 3-4o on Thursday evening October 29th.

   
   
   

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.


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October Moon at Descending Node

   Tuesday October 20th the 4-day old waxing crescent Moon crosses 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 date of the descending node the waxing crescent Moon will be over the southwestern horizon at sunset local time. Spread across the horizon from west to east are Jupiter, Saturn, Dwarf Planet Ceres, Neptune, and Mars.

   
   
   
   
   

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.


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Saturn at 2020 Eastern Quadrature

   Sunday October 18th the position of the planet Saturn with respect to the Earth and the Sun places this ringed planet at what is called eastern quadrature. Saturn is at a 90 degree angle from us as this graphic shows. Think first quarter Moon as that is a fair comparison of the relative positions. At this position Saturn follows the Sun across the sky from east to west as the Earth is rotating, meaning that Saturn rises after the Sun and sets after the Sun.

   Where is Saturn now? Saturn is over the southern horizon at sunset and is about 6o east (to the left) from the planet Jupiter. Further east is the Dwarf Planet Ceres, then Neptune, and over the eastern horizon is the still brightly shining Mars.

   
   
   Learn a little (or a lot) more about Saturn by visiting the Cassini at Saturn mission web site. Click here to go to the Cassini Mission web site.

   This is a short 5 minute video I made as part of a live musical performance called “Orbit” that I was part of in May 2011. This is a piece from the much longer tour of the solar system performance and video and shows Saturn and some of its moons as viewed from the Cassini spacecraft that month.

   
   
   

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.


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Mars at 2020 Opposition

Mars at Opposition   Tuesday October 13th Mars will reach a point in its orbit around the Sun where it is at opposition relative to the Earth. At opposition The Earth is between the Sun and Mars, or for that matter, between any of the outer planets and the Sun. At opposition both the Earth and the planet at opposition will have near identical heliocentric longitude. The opposition of Mars sometimes happens around the time that Mars is at its respective perihelion, closest to the Sun. If opposition happens during or near when the Earth is at its respective aphelion, furthest from the Sun, (first few days of July) then Mars will appear larger relative to when these dates are further apart.

Where is Mars Now?

What is opposition?
orbital-positions   The outer planets reach opposition when the Earth has moved into a position with the Sun on one side and the outer planet on the other side. Because all planets orbit in the same direction (toward the east), and all follow orbits that are slightly more elliptical than circular, oppositions occur at regular intervals of about 12 months (except for Mars). Mars is considerably closer to Earth and is moving faster than the other outer planets, so it takes approximately 26 months for Earth to catch up with Mars for an opposition.

   
   
   

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.


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Mercury- Spica & Moon – Antares

   Tuesday September 22nd shortly after sunset local time look toward the western horizon for the innermost planet Mercury to be about 1o from the bluish-white star Spica in Virgo the Harvest Maiden. The two should make for an interesting comparison in apparent magnitudes with Spica at 0.96 and Mercury with a -0.01 apparent magnitude.
   The nearly first quarter but still waxing crescent Moon will be about 7-8o from the reddish star Antares in Scorpius the Scorpion. Both are positioned over the southern horizon.

   
   
   

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.


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Neptune at Opposition – 2020

   Friday September 11th the outer planet Neptune reaches a position in its orbit around the Sun when it is on the opposite side of the Earth from the Sun. This coincidentally is known as opposition, and it is an orbital position which only the planets further from the Sun than the Earth may reach.
   At opposition an object orbiting the Sun beyond Earth’s orbit rises and sets in a fashion similar to our Moon when it is at full phase, in that the object at opposition rises at sunset and sets at sunrise.
   Currently Neptune rises at sunset and by late evening is over the southeastern horizon. Neptune has an apparent magnitude of 7.88 so it is beyond unaided-eye visibility but could be visible with large aperture telescopes or with a camera.

   
   
   

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.


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