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.

Follow the Arc to a Pulsar!

   During Spring in the northern hemisphere, the seven bright stars that form the Big Dipper are easily seen high over the northern horizon. Located at the hindquarters of the Great Bear (Ursa Major), this asterism (group of stars) has long been used as a celestial guide by travelers. During the American Civil War, slaves memorized a song called “Follow the Drinking Gourd” that helped them locate the stars that would point their way to freedom. By walking in the direction of the ‘drinking gourd’ stars the escaping, freedom seeking slaves, would be following a northerly route taking them away from the slave states to the free states to the north, or to Canada.
   There is an ‘old’ Astronomical saying, a sort of memory aid, for finding at least two constellations by way of their alpha, or brightest star in their respective constellation. In Bootes the Herdsman there is the orange-reddish star Arcturus, and in Virgo the Harvest Maiden the bluish-white star Spica. The saying – “follow the arc to Arcturus, then speed to Spica” is how you connect these two stars with the curve, or arc, in the handle of the Big Dipper.
   Simply look toward the northeast to find the 7 stars making up the Big Dipper. Then look for the curved handle and follow the arc or curved handle toward Arcturus and then continue on to Spica. This is typically done during the Northern Hemisphere spring and summer season when Bootes and Virgo are in the evening skies.
   While you are looking toward this region of the sky, you can also investigate some of our neighboring solar systems.
   Scientists now believe that two sunlike stars in this region have at least one orbiting satellite each, and that a nearby pulsar could have up to three satellites. Just below the bowl of the Big Dipper lies 47 Ursa Majoris, a star with an orbiting object estimated to have two to three times the mass of Jupiter and a revolution rate of 1103 Earth days. Near the northern boundaries of Virgo, an object orbiting around 70 Virginis is estimated to have six to seven times the mass of Jupiter and a revolution rate of 117 Earth days. Although the objects themselves are too far away to be seen, the suns around which they orbit are visible to the naked eye.
   A third solar system you could direct your attention to is also within the boundaries of Virgo. Unlike the other two solar systems, the objects in this system orbit a pulsar, PSR 1257+12. A pulsar is a small, extremely dense, and rapidly rotating neutron star, a remnant of a massive star that has collapsed into itself following a supernova event. PSR 1257+ 12 gets its name from its celestial coordinates, 12 hours 57 minutes right ascension and 12o north declination. This pulsar is one of at least several known pulsars in our galaxy and this one has an estimated diameter of 16 km, and a mass that is one to two times that of our Sun.
pulsar   Pulsars earn their name from the radio waves they emit, which we receive in regular pulses. Pulsars emit radio waves as a narrow beam, much like the beam of light emitted from a lighthouse. Just as direct light from a lighthouse sweeps past a point regularly, so does the beam of radio waves emitted from a pulsar. PSR 1257+ 12 emits radio waves that reach the Earth with at an interval of 6.2 milliseconds. Because we receive pulsed radio waves from a pulsar as a result of its rotation, we know a pulsar’s pulse interval coincides with its period of rotation. This means that PSR 1257 + 12 rotates every 6.2 milliseconds!
kepler   Exo-solar systems and their planets have been detected through various methods with the greater majority of these exo-solar systems being discovered by the Kepler orbiting observatory. To date more than 1,000 objects have been confirmed as an exo-planet, with more than 4,600 objects waiting confirmation.
distant-worlds-cover   Download a series of monthly star maps and data pages. Each monthly star map shows the location of many of the stars we know or are reasonably certain that are stars with their own planets. Click here to download the “Where Are the Distant Worlds Star Maps”. (2-3 Mb PDF)

   
   
   
   
   
   
   
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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.

Neptune at Solar conjunction

view-from-earth_neptune-solar-conjunction   Thursday February 26th the outer planet Neptune reaches a point in its orbit where it passes behind the Sun as we view this from Earth. Neptune, and the other outer planets, dwarf planets, or small solar system bodies, all eventually reach this position on the opposite side of the Sun known as solar conjunction.

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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.

Jupiter at Eastern Quadrature

1apr-jupiter-east-quad   On Tuesday 1 April the position of the planet Jupiter with respect to the Earth and the Sun places the solar system’s largest planet at an orbital position called eastern quadrature. Jupiter is at a 90 degree angle from the Earth as this graphic shows. Think first quarter Moon as that is a fair comparison of the relative positions. At this position Jupiter follows the Sun across the sky from east to west as the Earth is rotating, meaning that Jupiter rises after the Sun and consequently sets after the Sun.
   Where is Jupiter now? Click here to see a graphic showing Jupiter and the star field of northern hemisphere winter and spring stars. I purposely chose a later time, 11:30 pm CDT, because at about that time Saturn and Mars will be visible above the eastern horizon.

   This is a short 6-7 minute video I made as part of a live musical performance called “Orbit” that was performed at the Gottleib Planetarium in Kansas City Missouri in May 2011. This is a piece from the much longer tour of the solar system performance and video and shows Jupiter, Saturn and some of their moons as viewed from the Cassini spacecraft.

   
   
   
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.

Land of Many Lakes

titan   The only other place in the solar system that has liquid on its surface is Saturn’s moon Titan. However the liquid in the lakes on the moon Titan are not water as the temperatures on the surface average around -180o C (-292oF). Instead the liquid that falls as precipitation is in the form of methane, ethane, and other hydrocarbons. On Titan there is a cycle of evaporation, condensation, and precipitation that is reminiscent of the water or hydrologic cycle on our planet. Most of the liquids on Titan are found in the northern hemisphere.
   The NASA/JPL Cassini mission at Saturn folks just released a short video showing a simulated flyover of part of the region in the northern hemisphere of Titan where these lakes are located. Click here to go to the web site to see the flyover video as well as for additional information about the moon Titan. Click here to see the press release and to download the full picture of the moon Titan.
   Earth, by the way, is the only place we know of in the solar system where water is found in all three states of matter, at the same time.
   Saturn is currently in the morning skies rising about an hour before the Sun rises.
   
   
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.

3-D Model of Comet ISON’s Path

comet path   Here is a neat 3-D paper model of the path Comet ISON follows as it makes its way through the inner solar system. Follow the comet from its inbound approach and perihelion through part of its outbound path as it leaves the inner solar system.

    Use the link below to download the 4-page PDF document from the NASA Goddard web site.

http://svs.gsfc.nasa.gov/vis/a010000/a011200/a011222/Paper_Model_of_Comet_ISONs_Orbit.pdf

   
   
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.

Eclipse and the Nodes

Click on graphic to see it full size.

Click on graphic to see it full size.

   The solar eclipse on Sunday 3 November, will have been brought to us by the nodes. No the nodes are not a scientific nor a musical group, but rather the nodes represent an intersection between the orbital path of our Moon, or another planet, with the Earth’s orbital path, the plane of the ecliptic. There are two nodes or intersections, the ascending node and the descending node. There are two nodes because the planets as well as our Moon do not orbit the Sun on the same level, or plane as does the Earth. Their respective orbits are inclined (tilted) away from the plane of the ecliptic by varying amounts such that they will at times appear below or above the plane of the ecliptic. There will be two times each orbit around the Sun where the planet or our Moon will be on the plane of the ecliptic as it crosses moving from below setting up the ascending node or from above toward below, setting up the descending node.

Eclipse animation

Eclipse Animation

   So what is the significance of the nodes? The significance is all about timing. If the time of the new Moon phase, for example, occurs at or near the time for a node crossing then there will be a solar eclipse. Remember that at this moment the Moon is on the plane of the ecliptic and is more or less directly between the Earth and the Sun. More importantly, if the times are exact or very close there will be either a total solar eclipse or an annular solar eclipse. On 3 November the new Moon phase is 12:48 UT 6:48 am CST) and is at its ascending node nearly 6 hours earlier at 6:55 UT (12:55 am CST). The Moon makes first contact with the Sun at 10:04 UT (4:04 am CST); maximum eclipse, mid-eclipse, is at 12:46 UT (6:46 am CST); and the eclipse officially ends with last contact at 14:27 UT (8:47 am CST).
    To sort of complete this story, if there is a solar eclipse, no matter how total or less than total, there will be a lunar eclipse two weeks away at full Moon phase. Eclipses occur in pairs so this pair started with the penumbral lunar eclipse last month at full Moon on 18 October.
Moon Grazing the Earth's Shadow

Moon Grazing the Earth’s Shadow

Since that occurred about 26 hours before the Moon was at its descending node the angle the Moon followed through the Earth’s shadows only had it ‘graze’ the less noticeable outer penumbral shadow. Unless you knew about it you would have not noticed a slight dimming of the reflected moonlight. And, because the Moon’s orbital path is inclined, this lunar eclipse which was at descending node means that the 3 November solar eclipse will be at its ascending node – which it will be.

   Mercury is also in the picture because it too is at its ascending node and just a few days ago Mercury was at inferior conjunction. Had these two, ascending node and inferior conjunction, coincided we would have had a transit of the Sun by Mercury.
   
   
   
telescope
   
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.