Pluto at Opposition

orbital-positions   Monday July 6th at 10 UT (5 am CDT) the Dwarf Planet Pluto will be at opposition. All outer planets and other solar system objects that orbit the Sun beyond the orbit of the Earth have opposition. At that orbital position the Earth is between the Sun and the outer solar system object, much like the Sun-Earth-Moon arrangement for a full Moon. At opposition the outer solar system object rises at the local time for sunset and sets at the local time for sunrise – again just like the full Moon.

   Where is Pluto and is Pluto visible to the naked eye? Pluto currently is above the teapot-shaped asterism for Sagittarius the Archer. It is located near a 3rd magnitude star, Xi2 Sagittarii, however Pluto has an apparent magnitude of 14.0 making it too dim to be seen in other than a large telescope or with time exposure images.

Click here to learn more about the New Horizons mission and take part in the mission with some of the interactives created by NASA.

   
   
   
   

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.

#PlutoTime

eyes-screen   On July 14th, 2015 the New Horizons spacecraft will fly by successfully flew past the dwarf planet Pluto and its 5 currently known moons. An important part of the mission is the educational outreach – involving the public. So in addition to a new module added to NASA’s Eyes on the Solar System software, called Eyes on Pluto, there is now an online program, Pluto Time, that helps explain how bright it would appear at mid-day on Pluto and how that would compare with Earth.

A Picture or the Inverse Square Law?
   At the Pluto Time web site you enter your location and then are told the next time it will be ‘Pluto bright’ at your location. This seems to be around your local time for dusk or dawn – before sunrise or after sunset. So this picture from Tucson Arizona, facing northwest toward the Catalina Mountains, is as bright as it would be on Pluto during the daytime. Or at least according to the web site.

A Picture or the Inverse Square Law?
On the other hand, the average distance from the Sun for Pluto is about 5,906,376,272 km (3,670,052,066 miles) compared with the Earth’s average distance of 149,668,992 km (93,000,000 miles). Within the confines of the solar system distances like this are often referred to as units of AU or Astronomical Unit. One AU is the Earth to Sun average distance, while Pluto is 39.5 AU. Using the Inverse Square Law we can also determine how much dimmer Pluto is than the Earth, or how much brighter Earth is than Pluto.
inverse square law   The Inverse Square Law measures how much radiation, light in this situation, will decrease as distance from the light source increases. To calculate one simply inverses the distance value (makes it a fraction with 1 as the numerator) and then squares this fraction. For example if the distance were twice as much or were to double (2) then you would write it as its inverse, 1/2, and when squared (1/2)2 you would have 1/4. This would mean that if the distance were to double or be twice as much then the amount of light would decrease by 1/4th. 3 times would equal 1/9th; 4 times would equal 1/16th, and so on.
   What would it be like on Pluto? As of this posting Pluto is approximately 33 AU from the Sun (4,936,729,732 km; 3,067,541,639 miles). So the inverse square of 33/1: (1/33)2 = 0.00092 means that Pluto receives nearly 1100 times less sunlight than the Earth, or that mid-day on Pluto is that many times dimmer than than mid-day on Earth. The Sun in the sky above Pluto may look like this simulated view from the surface of Pluto suggests.

Here’s How to Make NASA’s Pluto Flyby a ‘Teachable Moment‘ for Students:

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.

Moon – Pluto Conjunction

   Friday May 8th the waning gibbous Moon and Pluto rise a couple of hours before sunrise local time. Both are located within the eastern fringes of the Milky Way and just above the teapot shaped asterism of Sagittarius. The Moon will be within a few degrees from the Dwarf Planet Pluto. While both objects may fit within the field of view of binoculars the apparent magnitude of Pluto, 14.8, means it is no where near being visible to the unaided eye and in reality its ‘dimness’ puts Pluto’s visibility into the realm of telescopes with a large primary mirror or lens. However just looking at the Moon means that some of the light your eyes receive comes from Pluto. And you are looking toward where the New Horizons space craft will be in about two months.

   The New Horizons spacecraft left the Earth in January of 2006 and as of May 8th the space craft will be 66 days from its flyby of Pluto and its five known moons. The flyby date of July 14th will be a significant event in the exploration of our solar system on many levels from a cool thing to do to the knowledge we will gain as we make our first up close and personal examination of an outer solar system object.

   
   
   
   

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.

Moon Meets Pluto

   Sunday morning, February 15th the thin 25.5 day old waning crescent Moon will be about 6o from Dwarf Planet Pluto. While Pluto, at 14th magnitude, will be much too dim to be visible to the naked eye, the Moon will be about 0.5o from an open star cluster. This is M-25, a 4th magnitude collection of around 100 stars. And next to a thin waning crescent Moon M-25 should be visible a faint smudge of light when viewed with binoculars.

   While looking at Pluto’s location you are looking where a NASA spacecraft, the New Horizons, will be in just a few months – 14 July 2015. And from the flyby through the Pluto system of 5 moons we will get our first good look at this ‘former planet’ and its near twin, the moon Charon.

   
   
   
   
   
   
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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.

On the 4th Night

              Happy   4th of   July!!                     

jul4-aphelion   Friday 4 July is not only the day we in the United States of America celebrate our country’s Independence Day, it is also the day that the Earth reaches aphelion, its greatest distance from the Sun. For the record we are closest to the Sun, perihelion, around the beginning of January.
   So despite the summer heat, humidity, and a late sunset there will be more in the skies this 4th than just fireworks.
 At around sunset look low toward the western horizon for 3 stars arranged in a short diagonal line. No it is not Orion’s Belt. The one on the lower left side is the planet Jupiter near the Gemini Twin stars.

Click on graphic to see it full size.

Click on graphic to see it full size.

 The nearly first quarter Moon is over the southwestern horizon and is just to the west (right) from the planet Mars and the bluish-white star Spica.
 Both Mars and Spica are close enough so that they fit within the field of view of 7×50 binoculars.
 Look left from this pair and higher above the southern horizon for the planet Saturn, one of 4 planets in our solar system with rings.

Click on graphic to see it full size.

Click on graphic to see it full size.

   If your viewing area is under dark enough skies, away from the light-polluted metropolitan area, then look toward the eastern horizon for the glow of the Milky Way as it rises. The teapot shape asterism for Sagittarius is above the southern horizon throughout this month and if the Milky Way is visible it looks like steam rising from the teapot’s spot. This graphic shows the location of Dwarf Planet Pluto. Pluto is also at opposition. Opposition for an outer planet is an arrangement of objects like a full Moon in that at opposition an outer planet is on the opposite side of the Earth from the Sun.
   While it is too dim to see with the unaided eye or even binoculars it is a neat idea to think about what Pluto looks like. I say this (actually write) because around this time next year NASA’s New Horizon spacecraft will be flying past Pluto sending back our first truly good look at this very distant solar system object.

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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.