Tag Archives: moon

An Experience of a Lifetime: My 1999 Eclipse Adventure

Back in 1999 I saw a total solar eclipse in Europe, and it was a life-altering experience.  I wrote about it back then, but was never entirely happy with the article.  This week I’ve revised it.  It could still benefit from some editing and revision (comments welcome), but I think it’s now a good read.  It’s full of intellectual observations, but there are powerful emotions too.

If you’re interested, you can read it as a pdf, or just scroll down.



A Luminescent Darkness: My 1999 Eclipse Adventure

© Matt Strassler 1999

After two years of dreaming, two months of planning, and two hours of packing, I drove to John F. Kennedy airport, took the shuttle to the Air France terminal, and checked in.  I was brimming with excitement. In three days time, with a bit of luck, I would witness one the great spectacles that a human being can experience: a complete, utter and total eclipse of the Sun. Continue reading

Some Pre-Holiday International Congratulations

I’m still kind of exhausted from the effort (see yesterday’s post) of completing our survey of some of the many unexpected ways that the newly discovered Higgs particle might decay. But I would be remiss if, before heading off into the holiday break, I didn’t issue some well-deserved congratulations.

The Jade Rabbit rover on the surface of the Moon, 15 December. Credit:Xinhua

Congratulations, first, to China — to the scientists and engineers who’ve managed to put a lander and a rover on the Moon. If you think that’s easy… think again! And they succeeded on their first attempt, a real coup. Now let’s see what science they can do with it, exploring a region of the Moon that apparently may offer answers to important questions about the Moon’s history. Specifically, by accident or by design, the rover is going to be able to explore an area of considerable geological importance, involving one of the Moon’s giant lava flows, a relatively young one (1-2.5 billion years rather than 3 billion or more).

Soyuz VS06, with Gaia, lifted off from Europe’s Spaceport, French Guiana, on 19 December 2013. Copyright: ESA – S. Corvaja, 2013

Congratulations, next, to the scientists and engineers of the European Union, who’ve put a fantastic telescope into space, destined to orbit the sun. The Gaia mission is aimed at doing the extraordinary: mapping, with ultra-high precision, the locations and motions of no less than 1 billion stars within our galaxy — nearly 1% of the total number. The distance to each of these stars will be determined by parallax — looking at how the positions of stars wobble, from the perspective of the spacecraft as it orbits the sun — and the real motions of the stars will be determined by how they drift across the sky, and by the Doppler effect for light.  This wealth of information will help scientists figure out the shape and history of the galaxy to a degree never previously possible.  Meanwhile, Gaia will also be able to do a lot of other science, picking up distant supernovas outside our galaxy, nearby asteroids orbiting our sun, and signs of planets around other stars, as well as brown dwarfs (small failed stars) that may be floating around between the stars. Gaia can even check some aspects of Einstein’s theory of gravity! Read here about all the wonderful things this mission can do.

Congratulations also to the scientists and engineers in Iran, who’ve apparently moved their rocketry program, and its potential application to human space flight, among other things, another step forward. A second monkey has made the trip to the edge of space, a suborbital trip. (Did the first survive? it’s not clear, and admittedly Iran is known for photo-shopping reality into supporting the story it wants to tell. Not that it matters; it took the US several tries, back over 60 years ago, before a monkey survived the trip, and the survival rate continued to be poor for a while. )  Anyway, it puts Iran well on its way toward its goal of a human in space by 2018.

And finally, congratulations to my own country, the United States, for having passed a budget deal. Not out of the woods yet, but at least it was bipartisan, and we’re not yet talking about another damaging government shutdown, or worse, default. Politics isn’t rocket science. We’ll have to hope our politicians can learn something from China: that it’s good to find some common and worthy goals to work toward together, rather than to fight about absolutely everything and bring the nation’s operations to a halt.

No Comet, But Two Crescents

I’m sure you’ve all read in books that Venus is a planet that orbits the Sun and is closer to the Sun than is the Earth. But why learn from books what you can check for yourself?!?

[Note: If you missed Wednesday evening’s discussion of particle physics involving me, Sean Carroll and Alan Boyle, you can listen to it here.]

As many feared, Comet ISON didn’t survive its close visit to the Sun, so there’s no reason to get up at 6 in the morning to go looking for it. [You might want to look for dim but pretty Comet Lovejoy, however, barely visible to the naked eye from dark skies.] At 6 in the evening, however, there’s good reason to be looking in the western skies — the Moon (for the next few days) and Venus (for the next few weeks) are shining brightly there.  Right now Venus is about as bright as it ever gets during its cycle.

The very best way to look at them is with binoculars, or a small telescope.  Easily with the telescope, and less easily with binoculars (you’ll need steady hands and sharp eyes, so be patient) you should be able to see that it’s not just the Moon that forms a crescent right now: Venus does too!

If you watch Venus in your binoculars or telescope over the next few weeks, you’ll see proof, with your own eyes, that Venus, like the Earth, orbits the Sun, and it does so at a distance smaller than the distance from the Sun to Earth.

The proof is simple enough, and Galileo himself provided it, by pointing his rudimentary telescope at the Sun 400 years ago, and watching Venus carefully, week by week.  What he saw was this: that when Venus was in the evening sky (every few months it moves from the evening sky to the morning sky, and then back again; it’s never in both),

  • it was first rather dim, low in the sky at sunset, and nearly a disk, though a rather small one;
  • then it would grow bright, larger, high in the sky at sunset, and develop a half-moon and then a crescent shape;
  • and finally it would drop lower in the sky again at sunset, still rather bright, but now a thin crescent that was even larger from tip to tip than before.

The reason for this is illustrated in the figure below, taken from this post [which, although specific in some ways to the sky in February 2012, still has a number of general observations about the skies that apply at any time.]

A planet (such as Mercury or Venus) with an orbit that is smaller than Earth's has phases like the moon but grows and shrinks during its orbit round the sun due to its changing distance from earth.  It is always largest when a crescent and smallest when full, and is brightest somewhere in between.

A planet (such as Mercury or Venus) with an orbit that is smaller than Earth’s has phases like the Moon.  The portion of Venus that is lit is a half-sphere (shown in light color); the portion of Venus we can see is a different half-sphere (dashed red lines); the overlap is shaped like the wedge of an orange and looks like a crescent in the sky.  But unlike the Moon, which is at a nearly fixed distance from Earth, such a planet appears to grow and shrink during its orbit round the Sun, due to its changing distance from Earth. It is always largest when a crescent and smallest when full, and is brightest somewhere in between.

So go dig out those binoculars and telescopes, or use Venus as an excuse to buy new ones! Watch Venus, week by week, as it grows larger in the sky and becomes a thinner crescent, moving ever closer to the sunset horizon.  And a month from now the Moon, having made its orbit round the Earth, will return as a new crescent for you to admire.

Of course there’s another proof that Venus is closer to the Sun than Earth is: on very rare occasions Venus passes directly between the Earth and the Sun.  No more of those “transits” for a long time I’m afraid, but you can see pictures of last June’s transit here, and read about the great scientific value of such transits here

A Solar Eclipse Tomorrow (Sunday)

Appropriate for General Readership

Tomorrow there will be a solar eclipse (i.e., the moon will pass between the earth and the sun, blocking the sun’s light.) Those of us on the east coast of the United States who wake up to a clear sky at dawn will see the rising sun partially eclipsed, as much as half blocked in many places. [Don’t forget that in the US the clocks are changing tonight, so dawn is one hour earlier, as the clock tells it, than it was today; in New York City sunrise is at 6:30 am tomorrow.] Meanwhile, a substantial partial eclipse will be visible across most of Africa, and a less substantial one in parts of southern Europe.  And a little sliver of central Africa will be fortunate enough to see one of nature’s most extraordinary spectacles: a total eclipse of the sun, where for a couple of minutes the sky suddenly goes almost dark, the stars come into view, and the pink prominences and silvery corona of the sun glow and shimmer in the darkness of the moon’s shadow.

Really, this ought to have been scheduled for Halloween.  Because if you didn’t know to expect a total solar eclipse, and you didn’t know what was going on, there’d be nothing more terrifying.

Remember: Except in the truly dark heart of a total eclipse, looking at the sun for even a few moments can destroy your eyes; either use specially designed “eclipse glasses” (ordinary sunglasses are completely unsafe) or use a pinhole in a piece of cardboard to project the sun’s image onto a piece of paper or a wall. [As I described here, carefully placed binoculars pointed at a piece of paper or wall will work too — but do not look through them!!! just let the sun’s image go through.] For those watching at sunrise, if there is cloud or haze in the east that dims the sunlight, you can look for a few moments — but make it very quick!

A Comet (Etc.) Well Worth Seeing

I’m pleased to say that last night I found comet Pan-STARRS, which is gracing the western sky just after sunset, and so I can recommend now that you all give it a try.  Binoculars will definitely make it easier to find, and allow you to see more of it.  It looks great!  Here are some thoughts on how to find it, appropriate if you’re in a country at roughly the same latitude as the United States.  (If you live far to the north or far to the south, you’ll need to get advice from someone who found it in a latitude similar to yours.  I don’t believe people in the southern hemisphere can still see it.) Continue reading

Testing, Testing: 12/12/12 12:12:12

This is a modified version of last year’s 11/11/11 article, in case you missed it.

Today is a special day — at least if you are fond of the number 12, and especially so if you’re willing to buy in to one of the oldest human pseudo-scientific pursuits: numerology. Oh, don’t get me wrong, I love numbers and I always have. When I was five years old I was mesmerized when my parents’ car reached 99,999.9 miles, and I think 12:34:56 on 7/8/90 is just a cool a time as anybody else does. But I do this with a sense of humor.

Unfortunately it happens that a few influential people attempt serious and consequential numerology involving the calendar — predicting disaster and convincing people to sell their homes and give away their belongings. Now that makes me mad. Outraged, in fact — because it’s often obvious from the way these predictions are generated that those who made them don’t understand much about the calendar, about time, about history and about astronomy or physics… and yet they speak with authority, an authority they haven’t earned and don’t deserve.

So as we celebrate this one-two-of-a-kind moment, let’s also remember, and enjoy, just how absurd it really is. Let us even count the ways. Continue reading


A number of transitions to talk about:

First, I’m participating in a panel discussion today (Thursday June 7th) on the transition that has seen me add science writer and popularizer to my resume’. Here’s the link… free tickets required, click here for details and ticketsSponsored by SoNYC (Science online New York City), panel discussion entitled “Reaching out of the Ivory Tower”, about the experiences of scientists who are reaching out to the public. Panelists: Ethan Perlstein, Sarah Weisberg, Matt Strassler, Jeanne Garbarino.  Location and time: Weiss 305, Rockefeller University, East 66th and York Ave. New York, NY, 7:00 PM.   Presenting science to the public in a digestible but honest form is something I feel is important, and I’ll have a few words to say about why I chose to do it now and why via a website and blog. And then I guess the floor will be open to questions, so come on by and ask one!

Reminder: again in New York, Saturday June 16th at 2pm, I’ll be giving a lecture (click here for details):  THE EINSTEIN OBSESSION: SCIENCE, MYTH AND PUBLIC PERCEPTION.

Next: I hope you all enjoyed seeing Venus in transit across the Sun Tuesday, in whatever method you chose. If you missed it live, there are of course opportunities to see films of the event — and they’ll save you time, since they’re all speeded up so that the hours pass in a minute or so. Nice views of Venus are complemented by several good-sized sunspots that are roughly the size of the Earth. Venus, you may recall, is the same size as the Earth, but as it was only a third as far away as the Sun yesterday, it appeared three times larger in radius (10 times larger in surface radius) than those sunspots. I managed to see it with the naked eye (with eclipse glasses), but just barely… so tiny! (By the way, if you missed my article on how a transit of Venus was used to obtain the first high-precision measurement of the distance to the sun, here’s the link.)

Here’s one of my own best shots, which I show you not because you can’t find better shots on the internet but because I have learned that most people do not realize you can get such nice views of the sun with so little work.

Venus in transit, at bottom.  Several sunspots dot the central region of the sun’s disk.  Photo of projection through binoculars onto white screen.  Image has been darkened slightly to sharpen contrast between sun and background.  Photo: M. Strassler 2012, all rights reserved.

It’s really quite easy.  And though there won’t be any more transits of Venus for us to see, there will be bigger sunspots, transits of Mercury, and solar eclipses to watch over the coming 15 years, so you may as well learn how to do this. You just aim the binoculars, big side toward the sun (as though someone were going to look at the sun — BUT DON’T LET ANYONE LOOK, of course), in the rough direction of the sun, wiggle the binoculars until the shadow of the binoculars becomes as small as it possibly can (which tells you they are aligned with the sun) and at that point the sun will shine through the two sides of the binoculars, giving you two images. Put a lens cover on one of the sides if you want to just get one image. Then let the image project onto something white and smooth that can serve as a screen. By moving the screen forward or back you can get a larger or smaller image; by using the focus on the binoculars you can bring the image of the sun into focus. Works great!

Here’s a picture, taken in a similar way, from the annular eclipse last month — a transit of the moon, even though we don’t usually call it that — taken the same way. I like this shot (though focus is imperfect and it was taken from a funny angle) because where the moon’s shadow touches the sun’s limb you can see a bit of light shining between mountain ranges on the moon!

A few seconds before annularity begins during the annular eclipse of the sun on May 20, 2012. Note, in the region where the moon’s silhouette touches the sun’s limb, a patch of sunlight shining through the mountain ranges on the moon. Light and dark regions at left and right of photo are due to shadows on the projection screen.  Photo: M. Strassler 2012, all rights reserved.

Venus, passing between the Sun and the Earth on Tuesday, has now transitioned from an object in the evening sky to one in the morning sky; if you want to see it, large and a very thin crescent through binoculars, you’ll need to get up early, before sunrise.  Not yet, though; it will be a few days before Venus is far enough from the Sun to pick out in the dawn sky.  For now, you can see Venus via the SOHO satellite, which blots out the sun so what’s nearby can be observed.

A final transition: Ray Bradbury died. Bradbury was one of the 20th century’s great science fiction writers, and I especially enjoyed reading his stories because he didn’t write classic geeky science fiction. His work was much more thoughtful and human than that. I think one could make a case that what made his writing unique was that he didn’t separate science from the rest of life.  It’s a good example for the rest of us to follow.

The Longest Sunset

What would the Grand Canyon look like if it had sunset light without the sunset shadows?  Sunday’s annular solar eclipse provided a hint of an answer:

The Grand Canyon from the North Rim (Cape Royal), during the annular solar eclipse of May 20th, 2012, at maximum eclipse (“ring of fire”). Photo Matt Strassler, all rights reserved.

Quite a first visit to the North Rim of the canyon.  Maximum eclipse occurred an hour before sunset, and the sun set with a small piece of the moon’s silhouette still covering its disk.  As a result, the amount of sunlight remained low for the entire hour, bathing the canyon in the low light that allows its layers of color and geological time to be more easily seen.

Meanwhile, in the other direction the sun was still far too bright to look at with the naked eye, or photograph without a filter. Lacking both a proper filter and a tripod, this is all I could manage with my camera, I’m afraid:

The annular eclipse of May 20th, 2012, showing the moon traveling across the sun, along with various unfortunate camera and filter effects. What can I say? I’m an amateur photographer. Photo Matt Strassler, all rights reserved anyway.

I think that when you look at photos of an eclipse (certainly I find this for myself) it is easy to miss the visceral nature of the experience. When you are watching it happen, you can see (through a proper filter, or with a projection), second by second, the slow but steady glide of the moon across the sun. You can detect the ring of sunlight changing shape, from a perfect circle to one that is thicker on one side than the other, and finally turning back into a crescent. The process is a dynamic one, as well as a visual feast. And this is part of what makes it so beautiful — not just what one sees with the eyes, but what one feels as a witness to the steady motion of the heavens.

[p.s. don’t miss the other two crescents to see right now: crescent Venus and crescent Moon near each other in the western sky tonight!]