Sunday, November 22, 2015

Hot Discovery: Venus-like Planet around Red Dwarf Star

A newly discovered planet is as hot as your oven at full strength and takes less than two days to orbit its star.

As the number of confirmed planets orbiting other stars nears 2000 (when just twenty years ago, that number was zero), we are finding many planets that are not like any we know in our own solar system. The new planet orbits a red dwarf, a star 200 times fainter than our Sun, called GJ1132. (GJ stands for Gliese-Jahreiss, the name of two German astronomers who produced a remarkable catalog of the stars closest to our Sun.)

Astronomers used telescopes around the world to pin down the characteristics of the new planet, which is just 39 light years away, very close by cosmic standards. It turns out to be a rocky planet, a little bigger and more massive than Earth.

But it is so close to its star it takes only 1.6 days to go around. (In other words, a year on that planet would be just 1.6 Earth days. That means an Earth 10-year old would be about 2280 years old on that planet!)

At so close a distance (only a million and a half miles away from its star), the planet experiences temperatures on the order of 450 degrees Fahrenheit. So it reminds us more of superhot Venus in our solar system than our own Earth. Interestingly, other planets known to be rocky that we have discovered orbiting other stars are even hotter. (Hot, close planets are easier to find, so they are over-represented among our early discoveries.)

Still, if for some reason, you need a turkey cooked really fast this week, perhaps a quick trip to GJ 1132b (as the planet is boringly designated) would be in order. Or just give thanks that you live in a cooler planet which takes its time orbiting the Sun.

[P.S. The image is just an artist's impression. We can't photograph such small close in planets -- they are lost in the glare of their star.]

Monday, November 9, 2015

Pluto Has a Crazy Tumbling Moon (Great Video)

Pluto has five moons around it and one of them, it was reported today, spins 89 times for each orbit it makes around Pluto. Hydra, the outermost of Pluto's four tiny moons, takes 38 Earth days to go once around the dwarf planet. During that time, it rotates 89 times.

For a hypnotic video of the motion of all the moons, see:…/defau…/files/dps-slides-showalter1.mp4

(Note that on the video, the moons are not to scale. In real life, the outer 4 moons are much much smaller than Pluto and the giant inner moon Charon, which is about half of Pluto's size. But the motion you see on the video is real.)

Hydra is the purple object on the video. The moon colored yellow, called Nix, spins almost fourteen times during one of its orbits. (The colors mean nothing on the video; they just help our eyes tell the moons apart.)

Astronomer Mark Showalter of the SETI Institute, who discovered two of the moons, is part of a team that suspects that the tumbling of the moons is caused by the extra pull that the giant moon Charon adds to the pull of Pluto in this system.

Another interesting fact about the motions in the Pluto system is that Pluto's day is equal to Charon's month.  In other words, Pluto rotates at the same rate as its giant moon orbits it.  That means Pluto and Charon are synchronized -- one side of Pluto always has Charon above it as it turns, and the other side of Pluto never sees Charon.  

By the way, it also appears from the New Horizons data coming back to Earth that Hydra and Kerberos (the green colored moon) are each made of two smaller chunks of ice that "merged" into one close system early in Pluto's history. Perhaps all four of the small moons are the result of such mergers. So here are two chunks of cosmic material living together intimately for billions of years. Perhaps the Tea Party fundamentalists and Supreme Court Justice Scalia might not approve of such a "marriage" between icy chunks, but I think it's pretty cool.

Sunday, November 1, 2015

We Fly Through the Geysers Coming from Saturn's Moon

Last week, the Cassini spacecraft flew through the water geysers spurting from Saturn's mysterious little moon, Enceladus. NASA's steered the spacecraft to within 30 miles of the moon's surface and through the salt-water vapor that's coming up through the cracks of the moon's icy surface. How great that we can still maneuver the Cassini probe to do this after 11 years of orbiting Saturn!

Planetary scientists believe that there is likely to be an ocean of liquid water under Enceladus' crust. (The name, by the way is pronounced "En - salad - us," not as hard as it first looks.) You can see some of the deep cracks through which the water emerges in the foreground on our top image. Below is a drawing of how scientists imagine the moon's structure could be arranged inside.

We will know more about what the plumes are made of when the data are analyzed in coming weeks. Even from further away, previous flyby's have already identified some of the most basic chemicals that are the earliest building blocks of life in the plumes.

How a small frigid moon way out where Saturn orbits -- a moon only 300 miles or so across -- can have an underground ocean and geysers is still a puzzle, but it shows us that we should not take even the smaller moons in the outer solar system for granted.

As always, you can see the pictures in more detail if you click on them.  For more information on the Cassini mission, see: 

Sunday, October 18, 2015

My First Science Fiction Story Published

As some of you know, I have long enjoyed science fiction, both as fascinating reading and also as a nice addition to my introductory astronomy classes. For 30 years, I also kept a diary of science fiction ideas that occurred to me, and might make the basis of good stories.
In the last year or two, I have joined a writing group and am trying to create some SF short stories of my own. I have a full bulletin board of eloquent rejection slips from some of the finest science fiction magazines in print (as, I gather, all beginning writers must collect,) But now, one of my stories has been published, in a Mars-theme anthology called "Building Red," from a small independent press in St. Louis called Walrus Publishing (and the book is available on Amazon:…/…/1940442079 )
The story, based on a real discovery about Mars, takes place in part inside a cave on the flanks of one of the four giant volcanoes on Mars' equatorial bulge. Instead of the sanitized, squeaky-clean NASA version of a future Mars colony, I tried to imagine one that's crowded, smelly, and has its share of loners and misfits.
The story is entitled "The Cave in Arsia Mons" and it appears together with Mars stories by a number of writers, some of whom have a longer publishing record in SF than I do.

More generally, for a topical index to science fiction stories that have good astronomy in them, see my web page at: 

Sunday, October 11, 2015

Blue Skies on Pluto

The New Horizons team just released a great new image of Pluto in front of the Sun. If Pluto had no atmosphere, it would just have blocked the Sun's light for the camera. But Pluto's thin (but significant) atmosphere scatters blue light more than red, just like Earth's air does, and so we can glimpse blue skies (or at least blue haze) around Pluto in the picture.

The haze layers in Pluto's atmosphere (seen more clearly in the black and white photo below) are made of slightly larger particles than Earth's haze layers, a kind of alien soot.

The lower image, showing Pluto at sunset, shows how the haze has several layers in it. The atmosphere is a thin mixture of nitrogen, carbon monoxide, and methane. Not a place where you want to (or can) take a deep breath! Astronomers think the atmosphere of Pluto is a bit thicker when it's closer to the Sun in its 250-year orbit, and then freezes out when it moves away from the distant sun for most of its plutonian year.

Also on the lower image, you can see the contrast between the mountainous higher lands on Pluto, and then in the middle of the picture, the smoother frozen plains that interrupt them. Only about 10% of the images and data have been sent back by New Horizons so far, so we have much more to learn about the little planet we visited briefly in July.

(As always, click on the photos, to see more detailed versions. Feel free to pass the pictures and information on, if you like them.)

Sunday, October 4, 2015

"The Martian" and Other News of the Solar System

If you've seen, read, or heard about "The Martian" film or novel, you may know that it's a story by an engineer about survival on Mars. If you'd like some background on how author Andy Weir tried to make the story realistic, using known science, check out his talk at NASA's Ames Research Center at:

The image accompanying this post is a selfie of a real "martian" -- the Curiosity Rover on Mars, which took the pictures from which this great Mars image was assembled in August. If you click on the picture, you get a bigger version.

For a listing of other Mars science fiction stories with reasonable astronomy, you can download my one-page resource guide at:

A fantastic new image and movie of Pluto's giant moon Charon (with its mysterious red polar cap) can now be seen at: 

For those of you who are in the Northern California area, or have friends there, there are two exciting events coming up this week:
1) Dr. Carolyn Porco, the head of the imaging team for the Cassini mission at Saturn, is giving a free public lecture (with fabulous pictures) at Foothill College Wednesday night:

2) The Astronomical Society of the Pacific and Chabot Space Science Center are sponsoring an all-day Family Astronomy Festival in Oakland Saturday Oct. 10. See:

Sunday, September 20, 2015

A Total Eclipse of the Moon Sunday Evening September 27

I thought you might like advance notice of a very nice upcoming lunar eclipse visible next Sunday evening in North and South America and in the early morning in Europe and parts of Africa and west Asia. Below are the basics in the form of questions and answers.  All you need to enjoy the eclipse is clear skies and (on the American west coast) an unobstructed view toward the East.

Next week you will start reading media reports about this being both a “blood moon” and a “supermoon,” but don’t pay too much attention to that.  The Moon will be a bit closer to the Earth in its orbit than average, making it look a bit bigger, but the difference is not especially significant.  And every lunar eclipse could turn reddish, as explained below.  It’s rarely the color of blood, but the media love anything that can be connected to thoughts of violence.

The Sept. 27, 2015 Total Eclipse of the Moon

1. What Is Happening?

On Sunday evening Sept. 27, a total eclipse of the Moon will be visible from throughout the U.S. (and North and South America.) In a lunar eclipse, the full Moon & the Sun are exactly opposite each other in our sky, and the Earth gets between them. This means the Earth’s shadow falls on the full Moon, darkening it.  It’s a nicely democratic event; no special equipment is needed to see it (provided it’s not cloudy or foggy.) Plus it happens early in the evening; kids can watch & still be awake for school next day.

2. When Will the Eclipse Happen?

The table below is for the U.S. (for other countries and continents, see:  which can be set for your home location.) 

Partial eclipse starts
Moon not up
7:07 pm
8:07 pm
9:07 pm
Total eclipse starts
7:11 pm
8:11 pm
9:11 pm
10:11 pm
Total eclipse ends
8:23 pm
9:23 pm
10:23 pm
11:23 pm
Partial eclipse ends
9:27 pm
10:27 pm
11:27 pm
12:27 am

As Earth’s shadow slowly moves across the Moon, we first see only part of the Moon darkening (partial eclipse).  When our shadow completely covers the Moon, we see a total eclipse. The best time to start watching is about a 20 minutes before total eclipse begins, when much of the Moon is already darkened. 

NOTE: On the west coast, the eclipse will start low in the Eastern sky, so make sure your observing location has an unobstructed view toward the Eastern horizon.

3. What is Visible During a Lunar Eclipse?

As the shadow of the Earth covers the Moon, note that our natural satellite doesn’t become completely dark.  Some sunlight bent through the Earth’s atmosphere still reaches the shadowed Moon and gives it a dull brown or reddish glow.  The exact color of the glow and its darkness depend in part on the “sooty-ness” of our atmosphere – how recently volcanoes have gone off and how much cloud cover, storm activity, and human pollution there is around the globe. 

Once the Moon is totally eclipsed, the stars in the sky should become more easy to see.  What makes this eclipse a little bit unusual is that, by coincidence, it is happening just one hour after the Moon has reached the closest point in its monthly orbit around the Earth.  So the Moon will look a bit larger in the sky than usual.  (The media will be calling it a “supermoon,” but the effect is pretty subtle for the average person.)

4. Is it Safe to Watch, and How do I Watch?

Since the Moon is safe to look at, and eclipses make the Moon darker, there’s no danger in watching the eclipse with your eyes or a telescope.  (The dangerous eclipse is the solar one, where it is the Sun that gets covered.) And lunar eclipses don’t require you to go to a dark location.  Bring binoculars to see the Moon larger, but just your eyes are fine.  Since the total eclipse will last for an hour and 12 minutes, be sure to take someone along with whom you like to spend time in the dark!

5. What Can I Tell My Kids (or Kid Brother or Sister)?

Suggest that they take a careful look at the shadow of the Earth as it moves across the bright face of the Moon.  What shape is it?  The round shape of the Earth's shadow suggested to the ancient Greeks, more than 2000 years ago, that the Earth’s shape must be round too.  Eclipse after eclipse, they saw that the Earth cast a round shadow, and deduced that we lived on a round planet (long before we had pictures of it from space.)