Tag Archives: Solar System

NASA Space Place – Triple Treat

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in May, 2013.

By Dr. Ethan Siegel

2013february2_spaceplaceThe solar system is a busy place, with five wandering planets visible to the naked eye alone. When any two pass close by each other from our point of view, we see an astronomical conjunction, but on very rare occasions, three planets will find themselves grouped together: a triple conjunction. Towards the end of May, Mercury, Venus and Jupiter will treat us to the best triple conjunction in years.

On May 25th, Mercury will pass within 1.4° of Venus, then two days later Mercury comes within 2.4° of Jupiter, and finally on the 28th, Jupiter and Venus approach within 1° of one another. If it weren’t for the slight orbital tilt of our solar system’s planetary orbits, these conjunctions would all be occultations instead. During the nights of May 26th-27th, all three planets are visible immediately after sunset within the same 3° field of view, with the triple conjunction peaking in a triangular shape on the 26th. (For scale, the full Moon subtends about 1/2°.) The three planets appear close together for a few days more, making a line in the sky on the 30th/31st.

How does this happen? Mercury and Venus race around the Sun far faster than Earth, with Mercury completing more than four revolutions around the Sun for each one that Earth makes. At the same time, Jupiter is far slower, taking 12 years to orbit just once around the Sun. Jupiter’s been high in the sky during the early parts of the night, but steadily lowers throughout May as Earth continues to move away from it, approaching its maximum distance from Earth. Mercury and Venus, meanwhile, begin to move out from behind the Sun during May: Venus at the beginning of the month and Mercury in the middle.

Thus, during this triple conjunction, all three planets will be on the far side of the Sun, something that happens just 25% of the time in triple conjunctions involving Mercury and Venus! If you telescopically resolve these planets into disks, you’ll see our inner worlds in a nearly-full gibbous phase. Jupiter will appear largest in terms of angular diameter, followed by Venus and lastly by Mercury. Just a year ago, during its now-famous transit, Venus took up more than a full arc-minute in the sky; during this conjunction, it will just one-sixth that angular size and less than a third the apparent diameter of Jupiter. Nevertheless, Venus will still be more than six times as bright as Jupiter during this time, outshining all night-sky objects other than the Moon. Closer conjunctions of two naked-eye planets are frequent, but getting three or more like this happens just once or twice per decade, so don’t miss your chance to see it.

And speaking of occultations, The Space Place has a great kid-friendly explanation of the Venus transit and solar eclipses of 2012 at spaceplace.nasa.gov/venus-transit.

Dr. Ethan Siegel, a theoretical astrophysicist, is a professor at the University of Portland (OR) and Lewis & Clark College.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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Caption: The image shows the configuration of Mercury, Venus, and Jupiter in the western sky just after sunset on May 26, 2013. Insets show the relative size appearance of the planets on that date.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/

NASA Space Place – It Takes More Than Warm Porridge To Make A Goldilocks Zone

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in November, 2012.

By Diane K. Fisher

2013february2_spaceplaceThe “Goldilocks Zone” describes the region of a solar system that is just the right distance from the star to make a cozy, comfy home for a life-supporting planet. It is a region that keeps the planet warm enough to have a liquid ocean, but not so warm that the ocean boils off into space. Obviously, Earth orbits the Sun in our solar system’s “Goldilocks Zone.”

But there are other conditions besides temperature that make our part of the solar system comfortable for life. Using infrared data from the Spitzer Space Telescope, along with theoretical models and archival observations, Rebecca Martin, a NASA Sagan Fellow from the University of Colorado in Boulder, and astronomer Mario Livio of the Space Telescope Science Institute in Baltimore, Maryland, have published a new study suggesting that our solar system and our place in it is special in at least one other way.

This fortunate “just right” condition involves Jupiter and its effect on the asteroid belt.
Many other solar systems discovered in the past decade have giant gas planets in very tight orbits around their stars. Only 19 out of 520 solar systems studied have Jupiter-like planets in orbits beyond what is known as the “snow line”—the distance from the star at which it is cool enough for water (and ammonia and methane) to condense into ice. Scientists believe our Jupiter formed a bit farther away from the Sun than it is now. Although the giant planet has moved a little closer to the Sun, it is still beyond the snow line.

So why do we care where Jupiter hangs out? Well, the gravity of Jupiter, with its mass of 318 Earths, has a profound effect on everything in its region, including the asteroid belt. The asteroid belt is a region between Mars and Jupiter where millions of mostly rocky objects (some water-bearing) orbit. They range in size from dwarf planet Ceres at more than 600 miles in diameter to grains of dust. In the early solar system, asteroids (along with comets) could have been partly responsible for delivering water to fill the ocean of a young Earth. They could have also brought organic molecules to Earth, from which life eventually evolved.

Jupiter’s gravity keeps the asteroids pretty much in their place in the asteroid belt, and doesn’t let them accrete to form another planet. If Jupiter had moved inward through the asteroid belt toward the Sun, it would have scattered the asteroids in all directions before Earth had time to form. And no asteroid belt means no impacts on Earth, no water delivery, and maybe no life-starting molecules either. Asteroids may have also delivered such useful metals as gold, platinum, and iron to Earth’s crust.

But, if Jupiter had not migrated inward at all since it formed father away from the Sun, the asteroid belt would be totally undisturbed and would be a lot more dense with asteroids than it is now. In that case, Earth would have been blasted with a lot more asteroid impacts, and life may have never had a chance to take root.

The infrared data from the Spitzer Space Telescope contributes in unexpected ways in revealing and supporting new ideas and theories about our universe. Read more about this study and other Spitzer contributions at spitzer.caltech.edu. Kids can learn about infrared light and enjoy solving Spitzer image puzzles at spaceplace.nasa.gov/spitzer-slyder.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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Caption: Our solar system is represented by the middle scenario, where the gas giant planet has migrated inward, but still remains beyond the asteroid belt.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/

CNYO Observing Log: Baltimore Woods, 9 February 2013

Ryan Goodson, Larry Slosberg, and I joined Bob Piekiel for his monthly New Moon observing session at Baltimore Woods on his weather-alternate session (having lost Friday’s session to Snow Storm Nemo). What started as a remarkably cold session, which then progressed to a bitterly cold session, and then finally to an intolerably cold session (forcing us to close shop up around 8:30 p.m.), still provided some excellent views of the Winter Sky, including the Solar System‘s largest planet Jupiter right between the Hyades and Pleiades.

For those who haven’t ventured for a session, the view from the Baltimore Woods parking lot includes a clear zenith (what luck!), a tree to the North that extends almost up to Polaris (so one must walk around it to get the view of constellations below our North Star), low-lying trees to the West, then the warm orange glow (the only thing warm on the 9th) of Baldwinsville and Syracuse to the East-Southeast. As we’re mid-winter, the evening observing was obstructed occasionally by blindingly bright snowmobiles (but one had plenty of lead time to take cover).

The evening started early with a fly-by of the yellow-orange ball that is (from the ground, anyway) the International Space Station (ISS), right on schedule with the predictions from heavens-above.com:

Date Brightness Start Highest point End Pass type
[Mag] Time Alt. Az. Time Alt. Az. Time Alt. Az.
09 Feb -3.3 18:55:57 10° SW 18:59:16 68° SE 18:59:56 51° E Visible

Reaching a total session count of eight, the evening included several observations of Jupiter, noting specifically how quickly Io rushed from Jupiter as even 10 minute intervals progressed (the slow cooling of mirrors resulted in many returns of increasingly crisp views). A comparison of eye piece magnifications and field-of-views was performed with the Pleiades in Bob’s 11″ Schmidt–Cassegrain and Ryan’s 16″ NMT Dob. In both cases, one my my favorite doubles, Tyc1800-1961-1 (blue) and Tyc1800-1974-1 (orange), jumped right out from the center of the tea cup. The lesson learned from such an exercise is that magnification is not the key to observational astronomy – it is seeing all that you want to see in the field of view that is key to enjoying the Night Sky.

A second highlight of the evening included M35, an open cluster in Gemini that, at 2,800 light years away, still covers an area the size of the Full Moon. Clearly visible as a slight “smudge” in the upper-left corner of the eyepiece (so the lower-right corner of M35) at low magnification is the compact open cluster NGC 2158.

After Jupiter, the night belonged to the massive Orion Nebula (M42), a hydrogen cloud doubling as a stellar nursery. At a magnitude of +4.0, the fuzzy patch in Orion’s Belt is visible to the Naked Eye, increasing in density with small binoculars, and leading to magnificent views of filamentous nebulosity at low magnification in both telescopes. The splitting of the main binaries in Trapezium was trivial in Ryan’s 16″ NMT Dob even without a completely cooled mirror.

I noted to Ryan that, given the usual CNY winter conditions, “It’s a rarity to see Pegasus in the West.” The quintet of Sirius, Orion’s Belt, the Hyades, Jupiter, and the Pleiades was worth the visit with or without equipment. After 90 minutes of observing in cold, continually patchy skies, the temperature dropped precipitously, instigating a rapid retreat and scope packing by all attendees. The lessons learned – your gloves are never thick enough & always have a headlamp in the car for the end of the evening!