Mars and Saturn Line Up – Sort of

   Saturday June 9th two of the outer planets, Mars and Saturn, will be at the same heliocentric longitude of about 278o, 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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Jupiter at Opposition: 2015

Zooming in on Jupiter at Opposition   On Friday, January 6th, 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 – on Friday both planets will have a heliocentric longitude of about 137o.
   For those keeping track, last year Jupiter was at opposition on January 5th. 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 that 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. February’s full Moon, by the way, was on the 3rd.

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

   
   
   
[centup]
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars and Neptune at Heliocentric Conjunction

view-from-mars   Saturday December 13th the planets Mars and Neptune are at heliocentric conjunction with both planets having approximately the same heliocentric longitude of 336.8o. From a perspective above the solar system the two planets are in a straight line alignment from each other.

   
   
   
[centup]
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars and Jupiter at Odds – Heliocentric That Is

31oct-view-from-mars   Friday October 31st the planets Mars and Jupiter are aligned in an arrangement known as heliocentric opposition. The two planets are on opposite sides of the Sun and are approximately 180o apart in heliocentric longitude as measured around the celestial equator. Mars has a heliocentric longitude of approximately 310o, while Jupiter is at 130o. However the two planets are not necessarily at the same level (above or below) relative to the ecliptic. Mars, at 24.53o South Declination, is only a few days (26 October) past its maximum declination of 25o south of the celestial equator in Sagittarius. Jupiter, at 15o North declination in the constellation Leo the Lion is north of Mars by nearly 40o.

   
   
   
[centup]
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mars, Spica, and Uranus

   And before you say it John, it does not continue with “walked into a bar.”
   On Tuesday 25 March two of the outer planets, Mars and Uranus, will be at the position along their respective orbital path where they are on opposite sides of the Sun from each other. This is called a heliocentric opposition and is based on using the heliocentric coordinate system. This is essentially a horizontal system of 0-360 degrees as measured eastward around the Sun. Mars has a heliocentric longitude of approximately 192o compared with Uranus’s heliocentric longitude of 12o. If nothing else what I think is interesting is how the orbits of these two planets compare with each other. The banner graphic at the top of the page shows the radius of each each planet’s orbit. Mars is 1.6 AU from the Sun, while Uranus is 20.0 AU from the Sun.

Click on graphic to see it full size.

Click on graphic to see it full size.

   Easily visible in the pre-dawn skies is Mars, its nearby stellar companion, the bluish-white star Spica, the planets Saturn and Venus, as well as several bright stars of the late northern hemisphere summer season.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Jupiter at Opposition: 2014

Jupiter at Opposition   Today 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 – which today both have a heliocentric longitude of about 105o. When an object is at opposition it rises at approximately the same time as local sunset (see the banner graphic) 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.
Zooming in on Jupiter at Opposition   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. January’s full Moon, by the way, is on the 16th.

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

   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Heliocentric Opposition

   Today, Monday 11 November, Jupiter and Dwarf Planet Pluto will be at the position along their orbital path where they are on opposite sides of the Sun from each other. This is called a heliocentric opposition and is based on using the heliocentric coordinate system. This is essentially a horizontal system of 0-360 degrees as measured eastward around the Sun. Jupiter has a heliocentric longitude of 100 degrees compared with Pluto’s heliocentric longitude of 280 degrees. If nothing else what I think is interesting is how the orbits of these two planets compare with each other. The banner graphic at the top of the page shows the radius of each each planet. Pluto is 32.54 AU from the Sun, while Jupiter is only 5.17 Au from the Sun.

   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.