Uranus at Western Quadrature – 2020

   Sunday August 2nd 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 also this graphic. 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.

   
   
   

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Crescent Moon – Venus Close Conjunction

   Friday morning June 19th about an hour before sunrise look toward the eastern horizon for the 27.5-day old waning crescent Moon and the inner planet Venus. The two will be separated by about 1-2o and both will easily fit within the field of view of binoculars making for a striking view.
   You will be looking at a Moon that is about 24-hours from new Moon phase, and shines with an apparent magnitude of -8.90 compared with Venus shining with a -4.29 apparent magnitude.
   Off to the west over the eastern-southern horizon are the outer planets, Uranus, Neptune, Mars, and Dwarf Planet Ceres. Further to the west are the planets Jupiter and Saturn.

   
   
   

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Moon – Mars/Neptune Conjunction

   Friday June 12th and Saturday June 13th before sunrise local time look toward the eastern horizon for the waning gibbous Moon to be near the planets Mars and Neptune. On both mornings the 20-22 day old Moon will be within about 7-9o from the two planets. Depending on your binoculars all three may fit within the field of view. However given the range of apparent magnitudes the reflected sunlight from Neptune (7.88) and possibly from Mars (-0.20) will be overshadowed by the much brighter Moon’s apparent magnitude (-12.0).


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2 Mornings – 2 Conjunctions

   Monday morning June 8th in the hours before sunrise look toward the western horizon for the 17-day old waning gibbous Moon to be within a few degrees from the outer planet Jupiter, and a bit further to the east the planet Saturn. With binoculars this conjunction could be followed for the next two mornings as the Moon will have moved to the other side of the two planets and closer to Saturn by Tuesday morning.


   
   
   
   


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June Apogee Moon

   Our Moon reaches perigee, (closest to Earth), for this orbit, on Wednesday June 3rd. At that time the Moon will be at a distance of 28.56 Earth diameters, 226,406 miles (364,366 km) from the Earth.

   On the day of the perigee Moon the 13.3-day old waxing gibbous Moon rises a couple of hours before the Sun sets placing the Moon over the southeastern horizon around mid-evening.

   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)

   
   
   
   
   
   

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Moon – Spica Conjunction

   Tuesday evening the 10.5-day old waxing gibbous Moon will be about 5-6o from the blue-white star Spica in the constellation Virgo the Harvest Maiden. Both will fit within the field of view of binoculars.


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Mars – Saturn Heliocentric Conjunction – 2020

   Monday June 1st two of the outer planets, Mars and Saturn, will be more or less at the same heliocentric longitude of about 280o, and would be in what is called a heliocentric conjunction. Heliocentric (Sun-centered) coordinates uses an overhead view of the solar system with planet location given as degrees of heliocentric longitude. The heliocentric longitude is based on a view from the Sun and is given as the angle between a planet and the vernal equinox. The vernal equinox, 0o, is located within the constellation of Pisces the Fishes, and is the intersection between the ecliptic and the celestial equator.
   As the Earth revolves around the Sun it ‘gives’ the Sun its apparent motion eastward along the ecliptic. When the Sun crosses the celestial equator at this intersection it is moving north. At the crossing northern hemisphere winter becomes spring – the opposite seasonal change for the southern hemisphere.

   Despite having the same heliocentric longitude, when viewed from the surface of the Earth, the two show an east to west difference of about 2 hours of right ascension.

   
   
   

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June Qué tal in the Current Skies Now Available

   This month, June, planet viewing is best in the early morning hours before sunrise. With the exception of Mercury all of the visible planets are in the morning skies. Mercury moves out east from the Sun this month reaching its greatest eastern elongation and then rather quickly moves westward back to the Sun and inferior conjunction on July 1st.
   This month there will be a pair of eclipses staring with a Penumbral Lunar Eclipse on the 5th. As penumbral eclipses go this one will be barely visible as it occurs over parts of southern Europe, Africa, south Asia, and Australia. On the 21st the new Moon will pass across the Sun setting up an annular solar eclipse that will occur over parts of north Africa, the Middle East and Southeast Asia.
   And on the 20th the Sun crosses the ecliptic moving north starting Northern Hemisphere summer and southern Hemisphere Winter.
   Click here to go to the Qué tal web site.
   

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May Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Monday 18th. At that time the 26.5-day old waning crescent Moon will be at a distance of 31.88 Earth diameters 252,028 miles (405,600 km) from the Earth.

   On the day of the apogee the thin waning crescent Moon rises about 1-2 hours before sunrise local time. Looking carefully with binoculars you may be able to see nearby 4th magnitude star 20 Ceti, one of the many stars that are part of the constellation Cetus the Whale.

   

   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)

   
   
   
   
   
   
   
   
   

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Mars – Jupiter at Heliocentric Conjunction

   Saturday May 16th the outer planets Mars and Jupiter will reach a point in their respective orbit that has them at nearly the same heliocentric coordinates. This a system of tracking the planets as they make their 360o orbit around the Sun. Each Sun orbiting object’s orbital position is measured using degrees, minutes, and seconds of heliocentric longitude. Each object orbits the Sun at a daily rate determined by dividing 360o by the number of days an object takes to complete one orbit around the Sun.
   As the above graphic shows the two planets are arranged in a straight line out from the Sun. The Earth is not part of the line-up. This is a heliocentric view of their orbital positions with the Sun at the Center. A heliocntric longitude based view is not the same as a view from the surface of the Earth where there is a distinctly different view of the two planets.


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