Sunday, August 6, 2017

Eclipse of the Sun Coming in 2 Weeks! And Another in 7 Years!

The path from top left to bottom right is the Aug. 21, 2017 eclipse
The path from bottom left to top right is the Apr. 8, 2014 eclipse

In just two weeks, on August 21, all of North America will experience an eclipse of the Sun. The eclipse will be total on a narrow path going across the U.S. from Oregon to South Carolina. The rest of the continents will see a partial eclipse, with a big bite taken out of the Sun by the disk of the Moon.
If you don't get to see this one, there will be another U.S. total eclipse in only seven years (on April 8, 2024.) If you missed out getting a hotel room or a campground in the zone of totality for August's eclipse, you have no excuse now for 2024! (See the attached map; click on it to see it bigger.)
I've had the opportunity to do quite a bit of media outreach for the eclipse; you can:
1. hear me as part of the eclipse special on the "Big Picture Science" radio show:…/eclipsing-all-other-shows
2. see me speaking on the eclipse at the SkeptiCAL convention sponsored by the Bay Area Skeptics:
3. read my comments as part of legendary science journalist David Perlman's last science article (David, who covered science news at the San Francisco Chronicle, is retiring at the age of 99! May we all have a career as long and respected as his.):…/Total-solar-eclipse-to-create-…
This week many media and people are waking up to the coming of the eclipse at last. Our free 8-page booklet all about it and how to view it safely can be downloaded from the page: Do read through it to get hints about how best to see and explain this rare sky phenomenon.
A free app, called TOTALITY, can be downloaded from both the Apple and Android app stores, and it will tell you exactly when and how the eclipse will be visible in your location.
If you haven't yet gotten safe eclipse-viewing glasses, your first stop should be your local public library. (Thanks to the Moore Foundation and Google, our project to distribute 2.1 million eclipse glasses has gotten glasses to almost 7,000 public libraries nationwide.)
If your library doesn't have any, here is a page to tell you all the reliable sources of eclipse glasses that are certified to meet the standards for protecting your eyes set by eye-doctors:
And for kids, please forgive me if I mention our children's book, "When the Sun Goes Dark," now in its fourth printing. Copies have temporarily run out in some places, but the publisher has it at:
Here is wishing you clear skies for August 21.

Eclipse stamp issued by the US Postal Service
changes the picture you see when you touch it

Tuesday, July 11, 2017

New Hubble Image of Jupiter's Red Spot

Astronomers are eagerly awaiting new information about the Great Red Spot, the largest and most colorful storm in the atmosphere of the giant planet Jupiter. The Juno spacecraft just flew as close as 5600 miles over the Red Spot, and the information is coming slowly back to Earth. This giant storm is currently about 10,000 miles wide -- larger than the entire planet Earth -- although it is smaller than when the Voyager spacecraft flew by in the 1970's. Why it has been shrinking and why it's color is so vivid are mysteries planetary scientists are trying to solve. 
In the meantime please enjoy the attached Hubble Space Telescope image of Jupiter, taken on April 3, when the Earth was closest to Jupiter in its yearly orbit. The Red Spot is vividly clear on this wonderfully detailed image, taken from just a few hundred miles above our planet's surface.  (Click on the image to see it bigger.)

Wednesday, June 21, 2017

Eclipse Talk on YouTube and New Kind of Eclipse Stamp

We are exactly two months away from the eclipse of the Sun that is coming to North America on August 21, 2017. I gave an illustrated, non-technical talk on the eclipse in the Silicon Valley Astronomy Lecture series, and it is now available on YouTube at: The talk has lots of information and visuals on where and how the eclipse will be visible, how to watch it safely, and how the U.S. is preparing for the huge crowds that are expected in the narrow zone where the eclipse will be total.
   Yesterday, the U.S. Postal Service issued its first ever "thermochromic" stamp in honor of the eclipse. That means when you touch the picture, it changes. Clearly this is a stamp every science will want to have. You can get them at your post office or by mail through:
   If you have not planned for the eclipse yet, now is the time to start thinking about where you will be on Monday, Aug. 21 and how you and your family or colleagues will observe the eclipse. In the video, I explain what is happening and give suggestions for safe viewing techniques. (Remember, any time any part of the Sun is showing, it's not safe to look at with just your eyes or sunglasses.)
   Thanks to grants from the Moore Foundation and Google, three astronomy colleagues and I were able to distribute 2 million safe eclipse-viewing glasses to public libraries nationwide. Check with your library to see if they are participating. The free booklet for libraries can be downloaded by anyone at: 

Sunday, May 28, 2017

New Views of the Planet Jupiter

The first results are in from the Juno mission exploring the giant planet Jupiter, and there are many surprises.
Look at the beautiful image here (click on it to see it bigger), showing the first detailed views of Jupiter's south pole region. The colors are a bit exaggerated, but the structures are real. You are seeing giant cyclones and anti-cyclones, as large as 600 miles across! That's extreme weather the 11 o'clock news team doesn't even dream about.

I'll remind you that Jupiter is not a solid planet -- most of it is made of gas and liquid. Yet there is enough material inside the giant planet to make 318 Earths. Scientists did not know whether at its very center it might have a small solid core or not. Heat from within rises and various molecules move up and down, producing complex bands, zones, and storms in the upper atmosphere.
Additional Juno discoveries include that Jupiter has a bigger core than expected, but that it has a fuzzy-looking structure, as if it were not sharply defined. The giant magnet inside Jupiter that surrounds it with the most powerful magnetic zone of any planet was also found to be stronger than anticipated.
Furthermore, the northern and southern lights on Jupiter are excited not only by charged particles captured from space (as we have on Earth) but also, unexpectedly, from charged particles coming from inside Jupiter.
As usual, when we get better instruments focused on a world or process in astronomy, we find that some of our old assumptions or ideas will need to be revised. That's what makes astronomy so much fun.

Below is an image showing 14 days of the Juno spacecraft approaching and then moving further away from Jupiter's cloudy atmosphere. (Click on it to make it bigger.)

Sunday, May 14, 2017

A Weird-looking Moon in a Gap in Saturn's Rings

Since 2004, the sophisticated Cassini spacecraft has been orbiting Saturn, sending back remarkable pictures of the planet, its rings, and its moons.   Now, with its fuel running out, the little spacecraft is being directed closer to Saturn’s rings, to get us even better views of this spectacular region (before Cassini does a Kamikaze dive into Saturn Sept. 15th.)

The image above is a fantastic close-up of one of the strangest moons we have ever seen.  The small moon Pan orbits inside the Encke Gap, an emptier region in Saturn’s bright A ring (Saturn’s different rings are given letter names.)  Pan looks like a “flying saucer” – with a set of high ridges around its equator.  It's about 22 miles across at its widest point.

Astronomers think that Pan formed inside Saturn’s ring and, as it grew, its gravity helped clear out the material in the gap which it now rules.  But there was enough material still in the flat ring neighborhood that it fell onto Pan’s equator and made the giant ridges that make Pan so distinctive.

Over the next few months, as scientist program Cassini to dive again and again into the space between Saturn’s and its rings, we will continue to get better images of “things in the rings” (sounds like Dr. Seuss) than we ever have before.  It’s a fitting finale for a spectacular space mission.

The image below shows you the neighborhood.  You can see Pan, its shadow, the Encke gap, and the A ring.  

Sunday, April 16, 2017

A Mini-Pluto at the Edge of Our Solar System

Astronomers have better measurements now of what is turning out to be a smaller version of Pluto located so far away that it may take 1,100 years to orbit the Sun. Nicknamed D.D. (or DeeDee) for Distant Dwarf, this remarkable small world appears to be about 400 miles in diameter -- only about 1/4 the size of Pluto, but possibly still big enough to be round like a planet.
D.D. was found in the fall of 2016 by a team of astronomers led by David Gerdes of the University of Michigan. As so often happens in astronomy, they were looking for something completely different, but found D.D. as part of their work. Now they have used an array of radio telescopes, called ALMA, to measure D.D.'s size and also to estimate its temperature. Ninety-two times as far from the Sun as the Earth is, D.D. is thought to be at minus 405 degrees Fahrenheit (minus 243 degrees Celsius; or only 30 degrees above nature's limit, absolute zero.)

D.D. is part of a whole zone of icy objects out beyond Neptune (astronomers call them Trans-Neptunian Objects or TNO's,) About 2,000 TNOs are now known, but most of them are too small and irregular (knotty potato-shaped) to be called dwarf planets. Pluto, the first TNO dwarf planet, was discovered in 1930, but in the last decade of the 20th century and the first decade of the 21st century, others were found, including Eris, Makemake, and Haumea. (If the names sound unusual, it's because we are trying now to name these outer worlds after mythological beings from many cultures, not just the ancient Greeks or Romans!)
We need more observations of D.D. before we are ready to call it a dwarf planet. If you thought that Pluto was being insulted when we called it a dwarf planet, perhaps it will help you to know that Pluto is the "first" of a whole new category of worlds. Five dwarf planets are now officially recognized by the International Astronomical Union, and at least six other worlds out beyond Neptune may eventually be included in the group. It may be years before we know if D.D. will join them.

But it's wonderful to see the Sun's family growing in this way, with our new instruments and surveys able to find worlds that literally are "far out!"

Sunday, March 26, 2017

Two Million Free Eclipse Glasses through Libraries (and a Free Booklet)

As you may know, there will be a rare eclipse of the Sun on August 21, 2017, and it will be visible throughout the United States. A spectacular TOTAL eclipse will be seen on a narrow path (about 70 miles wide) from Oregon to South Carolina. The rest of the U.S. and North America will see a PARTIAL eclipse, where only a part (but a substantial part) of the Sun is covered by the Moon. To look at the Sun when part of it is showing, special (but not expensive) glasses are required or you could damage the sensitive tissue in your eyes.
Millions of people will need glasses on August 21, and for the last year I have been grappling with the issue of how to get glasses to as many people as possible. Now, I am delighted to tell you that several astronomy colleagues and I have been able to get funding for glasses to be distributed through public libraries nationwide.
Thanks to the generosity of the Gordon and Betty Moore Foundation near San Francisco and Google, two million safe eclipse glasses will be made available through public libraries. Each library will get a supply of glasses to share free of charge and a booklet all about the eclipse and how to explain it to the public. The booklet, which I wrote with my colleague Dennis Schatz, is now ready and can be downloaded free at:
The first part of the booklet explains all about eclipses, the August eclipse and when and how it will be visible in different parts of the country, and how to observe it safely. It's written for beginners in science, so we hope everyone can benefit from it. The second part consists of information to help librarians plan public programs around the eclipse.
You could do your city or town a big favor by taking the booklet or just its web address in to your local library and encouraging them to participate in the eclipse and the glasses giveaway. Libraries can register for the program (through the STARNet Library Network at the Space Science Institute) at the website:
If, for some reason, your library can't participate in the program, there is information in the booklet on how to get eclipse glasses from the companies that manufacture the certified safe glasses that will protect you and your family's eyes. This spring is the time to make plans for where you will be and what you will do when the eclipse arrives on August 21.