Last ticket to Neptune! Teeny weeny solar system discovered

Venus floats above an intersection in Duluth recently. Photo: Bob King

You never know when the cosmos is going to drop in. I was driving home the other night and spotted Venus high above a street intersection in eastern Duluth. It was business as usual on Earth as the brightest of the planets cast a few rays in our direction.

Tonight and tomorrow night we’ll be grateful for Venus’ presence, because it gives us a last chance this season to easily find the planet Neptune in binoculars. The two will fit in the same field of view of a typical pair of 7 x 50 or 10 x 40 binoculars for the next two nights.

Go out about an hour and a half after sunset when the sky is dark and point your instrument directly at Venus. The planet is some 60,000 times brighter than Neptune, so don’t stare at it too long otherwise you might lose the night vision you’ll need to see the much fainter Neptune.

Venus and Neptune in a typical pair of binoculars with a 5-degree field of view Jan. 12 and 13th. Venus moves a significant amount in a day's time, Neptune very little because it's much farther away. This view has northeast at top, the way the sky would look facing the planet at nightfall. Created with Stellarium

Using the chart above, navigate upward from Venus to the 7.5 magnitude star and then up from there to another dim “star”. That faint point of light, shining at 8th magnitude, is Neptune, the solar system’s most remote planet currently 2.9 billion miles from Earth. Venus is breathtakingly close in comparison at just 114 million miles. After tomorrow night, Venus and Neptune pretty much part company with love goddess continuing its ascension in the western sky and the god of the sea sinking lower in the west. I love the poetry of the brightest planet in the solar system helping us find the faintest.

This artist's conception compares the KOI-961 planetary system to Jupiter and the largest four of its many moons. The KOI-961 planetary system hosts the three smallest planets known to orbit a star beyond our sun (called KOI-961.01, KOI-961.02 and KOI-961.03). The planet and moon orbits are drawn to the same scale. Credit: Caltech

Stepping outside our own solar system, NASA’s Kepler mission has just discovered the tiniest solar system beyond the sun. Three little rocky planets with diameters of 6,160, 5,765 and 4,500 miles were recently found orbiting the red dwarf star KOI-961.

The latest discovery comes from a team led by astronomers at the California Institute of Technology in Pasadena. The team used data from the Kepler mission, along with follow-up observations from the Palomar Observatory in California and Keck Observatory atop Mauna Kea in Hawaii.

This artist's concept depicts the new solar sytem, so compact it's more like Jupiter and its moons than a star and its planets. Credit: NASA/JPL

Kepler found the new system through patient observation of 150,000 stars in the Northern Cross region of the sky looking for tiny but measurable dips in brightness caused by crossing planets. Even though the new trio of mini-worlds orbit a star cooler than the sun, they’re still too close and too hot to be in the habitable zone. All take less than two days to circle their host star, which is just 1/6th the size of the sun.

What I find exciting about the news is the simple face that red dwarfs have solar systems. As you might guess by their name, dwarfs are smaller and cooler than the sun. They have only between 10-50% of the sun’s  mass and surface temperatures around 6,700 degrees F versus the sun’s 10,000. While red dwarfs are rather faint and inconspicuous, they make up for their diminished status by comprising the vast majority of stars in the universe. They far outnumber the bigger, shinier stars we see in the night sky. The closest red dwarf to Earth is Proxima Centauri in the Alpha Centauri system. Though only 4.24 light years away, you need a small telescope to spot it.

Since red dwarfs are so numerous, the Kepler discovery hints that planets might also be extremely common. Let’s see now. There are at least several hundred billion stars in the Milky Way, so the potential number of planets likely numbers in the billions in our galaxy alone.

The second amazing fact about this meek class of stars is that they live almost forever. Longer than the age of the universe anyway. Being small and relatively cool, red dwarfs burn their hydrogen fuel with great frugality. While the sun in its present form might be around for a total of 10 billion years,  red dwarfs stick around for hundreds of billions of years. Any red dwarfs that formed in the early years after the Big Bang are still with us today. Since a steady energy output over a long period of time is important for life to begin and subsequently evolve into its wonderful and varied forms, planets orbiting red dwarfs would seem the ideal places to begin searching for telltale signs of its existence.

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