Saturn at Western Quadrature – 2020

saturn-west-quadrature   Tuesday April 21st, the position of the planet Saturn with respect to the Earth and the Sun places this ringed planet at what is called western quadrature. Saturn is at a 90 degree angle from us as this graphic shows. Think third quarter Moon as that is a fair comparison of the relative positions. At this position Saturn leads the Sun across the sky from east to west as the Earth is rotating, meaning that Saturn rises before the Sun and also sets before the Sun.

Saturn currently is within the constellation of Sagittarius the Archer as this graphic shows. From the northern hemisphere, looking toward the southern horizon, you can find Saturn over the southeastern horizon about midway between Mars to the east, left, and Jupiter to the west, right.

Learn a little (or a lot) 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”. 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.

An ‘Old’ April Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Monday April 20th. At that time the new Moon will be at a distance of 31.86 Earth diameters 252,563 miles (406,641 km) from the Earth.

   On the day of the apogee Moon the 27.2-day old thin waning crescent Moon will be rising about 1 hour before the Sun rises and if spotted could become a personal record for seeing an ‘old’ Moon.

   While out looking for the Moon there are several planets arranged across the southern and southeastern horizon. They are arranged west to east (or east to west) along the ecliptic, the Earth’s orbital path around the Sun, as the two graphics below are showing.

   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” in NSTA’s Science Scope Magazine.

   
   
   
   
   
   
   
   
   

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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Morning Conjunctions

   This morning the 21-day old last quarter Moon was a few degrees from the outer planet Jupiter. As the Moon continues its eastward orbit, waning through the crescent phases, it will pass by Mars and Saturn, then 2 days later the waning crescent Moon will be close to the Dwarf Planet Ceres.



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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Jupiter at Western Quadrature

   Tuesday April 14th the ringed giant gas planet Jupiter reaches the point along its orbit around the Sun where Jupiter would be described as being at western quadrature. It is at a 90o angle relative to the Earth and the Sun.

   Where is Jupiter currently? Jupiter rises several hours before the Sun rises and is located within the eastern side of the constellation Sagittarius the Archer. Very noticeable is the 21-day old last quarter Moon which rises just ahead of Jupiter placing the Moon about 4-5o west from Jupiter.
   Off to the left from Jupiter, or further east, are the planets Mars and Saturn. Dwarf Planet Ceres, while not visible to the naked-eye, has just risen above the horizon and within the next hour Neptune and then Mercury will rise.

   
   
   

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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April Moon at Descending Node

   Monday April 13th the 20-day old waning gibbous 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 waning gibbous Moon will be above the southern horizon at sunrise and will be near the eastern edge of the Milky Way. However the Moon’s reflected light dims out the glow of the Milky Way. To the east are 4 of the visible planets, Jupiter, Saturn, Mars, and just rising above the horizon the innermost planet Mercury. Dwarf Planet Ceres, and Neptune are also part of the ecliptic line-up but both have apparent magnitudes too dim to be naked-eye visible.

   For this orbit the waning gibbous Moon has also reached its southernmost distance south from the celestial equator of 23.8o.

   
   
   
   
   

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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The Moon and a Scorpion

   Saturday April 11th the 18-day old waning gibbous Moon will be about 6o from the reddish star Antares, the heart of Scorpius the Scorpion. Both will be over the southern horizon at sunrise local time. Joining the Moon and Antares are the planets Jupiter, Saturn, 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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Venus and the Sisters

   This week will be one of those weeks of planet viewing that will be remembered. The early morning skies have 4 of the visible planets arranged along the ecliptic over the eastern to southern horizon. In the evening skies there is the inner planet Venus moving eastward away from the Sun and rapidly, at least in terms of orbital speed, toward the open star cluster the Pleiades. This is a group of several hundred stars bound together by their respective gravitational attraction, and is located on the shoulder of Taurus the Bull.
   Venus, as a planet closer to the Sun than the Earth, will move more each day than the apparent speed of the Sun, which is based on the Earth’s orbital speed of about 0.98o each day. Venus being closer to the Sun will move approximately 1.6o each day.
   So over the course of 2-3 days the planet Venus will move across the stars of the Pleiades as this animated graphic is showing. It is set for 1-day intervals from April 2nd to the 5th. As Venus moves across the stars it will make for a great view either through binoculars or telescope.


   
   
   

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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