Jupiter at Opposition: 2017

Zooming in on Jupiter at Opposition   Friday April 7th, the outer giant planet Jupiter reaches the point in its orbit around the Sun that places the Earth in between Jupiter and the Sun. This is known as opposition, and opposition is an orbital position that applies to solar system objects (outer planets, dwarf planets, asteroids, comets, etc.) orbiting the Sun beyond the Earth’s orbit. An object at opposition will have approximately the same heliocentric longitude as the Earth’s heliocentric longitude. So on Tuesday both planets will have a heliocentric longitude of about 167o.
   An opposition of Jupiter occurs approximately every 13 months because both Earth and Jupiter are moving. After one Earth Revolution, an Earth year, the planet Earth will be where it was the previous year at opposition with Jupiter. However Jupiter will not be there because it has moved during the past year as well. It will take the Earth about an extra month or so to catch up with Jupiter. Earth moves 360o each year while Jupiter moves approximately 12o each Earth year.

Sunset Local Time

Sunset Local Time

   When an object is at opposition it rises at approximately the same time as local sunset and that same object at opposition sets at approximately the time of local sunrise. In other words an object at opposition will be up all night from sunrise to sunset.
   Picture our Moon at full phase and how it is directly opposite the Sun, with the Earth in between. The full Moon in effect is at opposition but we call it the full Moon instead. And like Jupiter at opposition, a full Moon rises at sunset, sets at sunrise and is visible all night.


   Jupiter rising with Spica.
   
   
   
   
   
   
   
   
   
   
   
Take a brief tour of the Jovian (Jupiter) system. Music by Dark Matter.
Live recording of music written by Richard Johnson. Video by me!

   
   
   

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.

April Moon at Ascending Node

   Friday April 7th the waxing gibbous Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.


   On April 7th the 11-day old waxing gibbous Moon will rise with the constellation Leo the Lion and is located near the Lion’s tail, the star Denebola.

   Does our Moon actually go around the Earth as many graphics show? 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)

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 return to bobs-spaces.

A Night With the Lion

   Thursday evening April 6th and Friday morning April 7th the waxing gibbous Moon will rise and then set with Regulus, the brightest star in Leo the Lion. During the course of the night the Moon will pass within about 1o-2o from Regulus.

   Thursday evening April 6th, after sunset, look toward the west for a reddish appearing star. That is the planet Mars and about 2o to the east, left side, from Mars is Dwarf Planet Ceres, the closest of the dwarf planets. Not sure about Mars? Look for the Pleiades, an open star cluster with the brighter stars having a small dipper shape. Below the Pleiades is Mars.

   Thursday evening April 6th at sunset it may be possible to see the innermost planet Mercury in addition to seeing Mars and Jupiter, and at least with binoculars 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.

March Moon at Ascending Node

   Saturday March 11th the waning gibbous Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.

   On March 11th the 13.5-day old waxing gibbous Moon will rise with the constellation Leo the Lion and is located near the Lion’s tail.

   Does our Moon actually go around the Earth as many graphics show? 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)

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 return to bobs-spaces.

A Lunar Conjunction with a Dwarf Planet


   Thursday evening March 2nd watch for the 4.5-day young waxing crescent Moon to be about 2o away from Dwarf Planet Ceres. Seeing Ceres with an apparent magnitude of around 8 may be difficult when the Moon is this close, especially using binoculars. 2march-tele
   However with a telescope Ceres should resolve into a small disc shape as this simulated view with a 25mm eyepiece on a 6″ reflector shows. There are two 6th magnitude stars on either side of Ceres that could be used as reference points for Ceres location if you are following the Dwarf Planet as it moves along its orbit.

   
   
   
   
   

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.

February Perigee Moon

6feb-perigee_moon   The Moon reaches perigee, (minimum distance from Earth), this month on Monday February 6th. At that time the Moon will more or less be at a distance of 28.91 Earth diameters (368,816 km or 229,172 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 day of the perigee Moon 13-day old nearly full Moon rises just before sunset local time and is located near the feet of the Gemini Twins.
   These two animated graphics show the sky as viewed from Quito Ecuador at 0o latitude, and my home latitude of approximately 40o North. They show the sky at one day intervals starting with February 1st and ending with February 5th.


   
   
   *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.

January Moon at Perigee

10jan-perigee_moon   The Moon reaches perigee, (minimum distance from Earth), this month on Tuesday January 10th. At that time the Moon will more or less be at a distance of 28.4 Earth diameters (363,238 km or 225,705 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 day of the perigee Moon 13-day old nearly full Moon rises just before sunset local time and is located near the feet of the Gemini Twins.

   
   
   *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.