Crescent With Triangle

We’re on the trek home from my aunt’s funeral in Ohio today. Leaving the Greek restaurant (spanakopita!) just after sunset, the crescent moon made a lovely counterpoint to the triangle of Mars, Saturn, and Spica. Check out this western image tonight in the next hour if you can. The moon will be at the top of the triangle by tomorrow night. The triangle will remain a western sky feature for a few weeks longer.

This is a nice opportunity for newbie astronomers to note how Mars and Saturn “wander” compared to the background stars. Spica is the brightest in the constellation Virgo, and while not quite as bright to Earthling eyes, gives us an easy reference point to judge planetary movement. Our English word for “planet” comes from the Greek (πλανήτης, planētēs).

We got a very early start yesterday for this trip. Driving east on I-80, Jupiter was well overhead. Venus was a bright beacon. I thought I glimpsed Mercury low in the east before the lightening sky washed it out.

Keep your eyes on the sky–good things up/out there.

 

Satellite Imagination: Honoring a Wife

Pluto has been demoted from planethood, but before that determination and after, it has been carefully studied. As much as a point of light on a photographic plate can be studied. Clyde Tombaugh really picked a needle out of a celestial haystack:

Would you catch that without the arrows? Neither would I.

Seth Barnes Nicholson, discoverer of four satellites of Jupiter, studied that faint dot after Clyde Tombaugh’s discovery. His analysis suggested that faraway Pluto had about the mass of the Earth. A respectable planet, to be sure.

As the years passed, astronomers were able to discern a bit more about that white spot. Gerard Kuiper, another satellite discoverer, whittled Pluto’s size estimate down to about a tenth that of Earth–about the size of Mars. No idea how he did that. Other astronomers saw enough of a shift in the light to determine that Pluto spun on its axis giving it a day of about 153 hours. How they got that from a small white dot on a photographic plate, I have no idea on that either.

Two things happened by the mid-1970′s. First, NASA was looking at targeting Pluto for one of its Grand Tour missions to the outer planets. Second, Dale Cruikshank, Carl Pilcher and David Morrison of the University of Hawaii determined that Pluto’s surface was largely bright methane ice. And because a bright faraway object was likely smaller than a dark body at the same distance, Pluto’s size estimate was further reduced to about one-hundredth of the Earth. A bit smaller than the moon.

Enter James Christy. In 1978, the astronomer, a double star specialist, was looking at photographic plates snapped by the 61-inch telescope at the US Naval Observatory in Flagstaff, Arizona (USNOF). He found a bulge in the grainy image of planet Pluto. Since his specialty was observing distant stars revolve around each other, his best judgment was that Pluto had a moon. It orbited once every 6.39 days, the same as what astronomers thought Pluto’s day was.

Do you see the satellite in the discovery plate? It’s the lump appearing on different sides of the planet:

Christy checked some of the photographic plates in storage at the USNOF. Way back in 1965, someone marked an image, “Pluto image elongated.” But astronomers just assumed that it was a smudge or some error, human or instrument. Guess that might teach some people to jump to conclusions …

Most scientists agreed with Christy. But a few thought it might be a big mountain on the planet. After all, a lump is a lump, right? All skepticism was silenced in 1985, when the tilt of orbits permitted astronomers to verify, through changing light levels, that Pluto actually had a moon. And more, very rough maps were produced. By the time the Hubble Space Telescope was in orbit, there was no doubt, as you can see from this 1994 image:

No mountain, that.

Once scientists had verified a body in orbit around Pluto, it’s an easy matter to “weigh” both planet and satellite. Alas, Pluto came out on the short end again. The final determination was that it would take five-hundred Plutos to balance the scales with Earth. That new satellite was pretty hefty, relatively speaking. Twelfth largest in the solar system.

Let’s get to the name. Astronomers who discover things often get to name the object. It must pass muster with the IAU (International Astronomical Union). But as long as one keeps to the conventions, it’s likely to get approved. Christy’s colleagues at the USNOF were pushing for Persephone, the consort of the Roman god Pluto. But the discoverer wanted to honor his wife Charlene, familiarly known as Char. As it turns out, Charon is the name of the ferry operator in the Greek myths about the underworld. Greek pronunciation, however, is the hard “k.” Charon was approved. Though Mrs Christy is honored by many English-speaking astronomers who have picked up the soft “sh” sound. I pronounce it “sh.” I can appreciate honoring a wife.

I will likely not ever be a satellite discoverer. Asteroid, possibly. The list of asteroid names is ample. My wife’s is not on the list, though my daughter’s name is attached to minor planet number 51599. I don’t know how James Christy thought of his wife. If I were to indulge my imagination, my wife would be my star around which I spin. Maybe my wife and daughter a double star, and I would be a planet revolving around both. It doesn’t take much imagination to ponder that. I think you need more to see a lump on a black spot and think “satellite” rather than “mountain” or “mistake.”

 

An Inkling on Mercury

C.S. Lewis wrote of Mars and Venus, but not the solar system’s innermost planet. His good friend, J.R.R. Tolkien now has a namesake crater there, near the Mercurian north pole. The convention is that craters on that planet are named for artists and writers. I looked over this list for church musicians of the chant and polyphony stage, but only noticed des Prez and Monteverdi. What artists and writers do you find missing who should be included for names of craters?

 

Curious About Curiosity?

The site Universe Today as ample coverage of the Curiosity landing on Mars. You can catch the image of the parachute stage of the landing snatched from Mars orbit (left). There’s a movie picking things up after the heat shield was jettisoned. The first color image from the surface, too. Not only did Curiosity make it to the surface, but the heat shield, parachute and back shell, and the sky crane, too. I wonder if checking out the debris will be on Curiosity’s to-do list.

I was crossing my fingers on this one. I honestly thought Curiosity wasn’t likely to make it, given all the things that had to go right. But, like Jose Funes SJ of the Vatican Observatory, I’m happy about the success and looking forward to years of Martian roving.

 

Space Aquarium

I see the astronauts at the International Space Station are getting pets of sorts. More than pet fish, really. These little guys will help researchers determine the progress of bone and muscle loss in a microgravity (weightless) environment. That’s the one big issue that Mars mission thumpers don’t talk about a lot. Even though they insist the astronauts on long Earth-orbit missions exercise daily, nobody as yet has a handle on how to stop the human body from adapting to the sense of weightlessness one experiences off-planet.

These fish, Oryzias latipes, have already been taken into orbit on previous US shuttle missions and bred in space.

If it were me, I’d prefer a nice cat for a space station pet.

 

Another Polar Vortex

The Cassini probe spotted a vortex over Titan’s south pole. It’s now early spring in Titan’s southern hemisphere. Cassini will be watching seasonal changes carefully for the next several years.

This is not unique to dense atmospheres in the solar system. Saturn has one. Venus, too.

It’s so interesting that this phenomenon occurs not only on Earth (hurricanes) but on much warmer and much colder bodies.

Image credit: NASA/JPL-Caltech/Space Science Institute

 

Cloudy Transit

I took a dinner break at the polls around the time when the sun was dodging clouds over central Iowa. About a half-hour in, I had a few minutes of clear sun. Then I realized that maybe I could get something on the cell camera. Not great, but enough to remember the day.

About an hour into the transit, I focused binoculars onto a piece of paper:

Venus is the small dot in the lower left, just above the cloud drifting in.

About a half hour later, the sun emerged and I got three images in short succession:

My first solar eclipse was an 85% partial in 1970. My first-ever sighting of Mercury in 1974 was in a transit. Twenty years after that, I viewed an annular eclipse from southern Michigan. Today I added Venus. Another viewing checked off my list.

 

Another Day of Civic Duty

I wish I had known about being an election official years ago. I’d been waiting to get on jury duty forever. But at my older brother’s encouragement, I volunteered to work the 2008 elections after I moved back to Iowa. I never felt more of an American as on that day. I’ve gotten the call to do the party primaries June 5th. Not being a member of either major party, I can’t vote tomorrow. But I’m happy to facilitate the voting for others.

That being said, I’ll likely miss blogging for the first time this calendar year. As you see below, I’ve put up the other Faithful Four post.

Don’t forget about the transit of Venus tomorrow. I won’t be able to join the local astronomy club for it, but I’m bringing binoculars and a white sheet of paper to the polling place so I can look in on the last Sun-Venus-Earth alignment till 2117. 5pm Eastern time, if I remember right. Hope it’s sunny where you are.

 

Intergalactic Tidal Debris

Today’s Astronomy Picture of the Day features a pair of celestial objects, the beautiful Whirlpool Galaxy and its rump companion NGC 5195. Whirlpool is something of a man galaxy-eater. One of its spiral arms seems to be stabbing its companion. Note the haze-like streams, especially around NGC 5195. Those are thousands of stars stripped away by the interaction of gravity between two colliding forms.

The Mice Galaxies (Image credit: ACS Science & Engineering Team, NASA) have had a harder time of it:

Not only have stars been scattered, but note the “mouse” on the right. Those brighter blue star-forming regions have also been smeared across intergalactic space. They’ll produce another generation of new stars, but those nurseries will eventually fade and die over the next several million years.

What if Earth and its sun were in one of these streams? Instead of the Milky Way spread across the night skies away from cities, we might see a patch on just one side of the sky. Instead of two thousand stars to wish upon, there might be several dozen. Probably nothing as bright as the planets. Perhaps not evenly distributed as we see it from our perspective within a galaxy. That would change our mythology and our expression of it.

It is thought that our galaxy is on a collision course with the Andromeda Galaxy. If so, it’s still a very long way off into the future.

 

Tarantula Bursts With Stars

Astronomy Picture of the Day has been knocking me out this past week. Today they feature the Tarantula Nebula from the Hubble Heritage site, so big and bold we can see it with the unaided eye from across intergalactic space. Let the astronomers tell it to you:

No known star-forming region in our own galaxy is as large or as prolific as (this). Fortunately, (the Tarantula Nebula) can be seen clearly from Earth, and it is nearby enough for Hubble to resolve its individual stars. This allows astronomers the rare opportunity to study stellar evolution closely in the exotic, extragalactic context of a starburst.

The Hubble composite image comprises one of the largest mosaics ever assembled from Hubble photos, including observations taken by Hubble’s Wide Field Camera 3 and the Advanced Camera for Surveys. Hubble’s unparalleled eye for fine, intricate detail is composited with ground-based data that trace hydrogen gas (in red) and oxygen (in blue). These complementary observations of the Tarantula Nebula were taken with the European Southern Observatory’s 2.2-meter telescope in La Silla, Chile. NASA and the Space Telescope Science Institute are releasing this image to celebrate Hubble’s 22nd anniversary.

The image features scenes from the drama of star birth, from embryonic stars still swaddled in cocoons of dark gas to stellar behemoths that rage and die – regrettably, predictably – in blazing supernova explosions.

To give you a sense of scale, the nearest major stellar nursery to us is the Orion Nebula. If the Tarantula were that far away from Earth–about 1300 light years–it would spread across half the night sky.

Image credit: NASA, ESA, ESO, D. Lennon (ESA/STScI), and the Hubble Heritage Team (STScI/AURA). Do yourself a favor and go to the Hubble Heritage site and see the full sized versions there.

 

Big Drop

If all the earth’s water were gathered into one sphere, it would be slightly larger than Saturn’s number two moon, Rhea. According to this illustration, I can see it from my backyard. The USGS gives some helpful info here.

 

Tornado of Mars

Universe Today notes a neat video on the JPL website showing the actual image of a 12-mile-high tornado followed by an animation of what it would look like from a balloon observer on the red planet. Image credit: NASA/JPL-Caltech/UA

 

Hypervelocity Planets

An illustration of human willful ignorance of the vastness of space. This Universe Today piece titled “Can ‘Warp Speed’ Planets Zoom Through Interstellar Space?” Astronomer Avi Loeb:

These warp-speed planets would be some of the fastest objects in our Galaxy. If you lived on one of them, you’d be in for a wild ride from the center of the galaxy to the Universe at large.

…

Travel agencies advertising journeys on hypervelocity planets might appeal to particularly adventurous individuals.

I appreciate Dr Loeb’s willingness to appeal to the cultural consciousness to get people excited about the discovery of hypervelocity planets. And yet, because of the extreme distances, even a planet zooming along at ten million miles an hour would have a rather boring itinerary on the whole.

Such a planet would traverse our solar system in about a month. However, assuming it was on a beeline for the nearest star system, Alpha Centauri, at two percent of the speed of light, it would still take about two centuries to arrive. For another month-long tour. It would be like spending seven years cruising the high seas for every one day in port. And that’s only if the aim was perfect. Talk about Dorothy Day’s “long loneliness.”

 

On My Bookshelf: Astronomy Non-Fiction

Two short and enjoyable reads this past week. Last night I finished Alone in the Universe. John Gribbin takes the reader through a careful tour–in turn: the galaxy, the sun, the solar system, the Earth, the Cambrian Explosion, and human beings. A series of factors contribute to Dr Gribbin’s take that human beings are the only intelligent life form in the universe. Quite frankly, I agree. But I didn’t need this book to convince me.

The first five chapters deal with astronomy and they are absorbing. Chapters six and seven examine two momentous events: the explosion of life about 530 million years ago and the volcanic resurfacing of Venus around the same time. Dr Gribbin makes the case that the latter was the instigation for the onset of Snowball Earth. His theory is that a moon-sized object hit Venus, caused a worldwide volcanic resurfacing of that planet (the evidence of the resurfacing is not in doubt) but that the debris from that collision may have been enough to tip the entire planet Earth into an ice age. Eventually Earth’s own build-up of carbon dioxide and methane from our own volcanoes thawed the planet. Life bloomed as a result.

The blooming of life–of hard-shelled fossils–in undeniable. Dr Gribbin is going to need more than two pre-Cambrian events to show conclusively there is a connection between them. Earth has teetered on going Big Snowball earlier in its history. It would be interesting to nail down those earlier periods and see if there is a correlation to the infusion of dust into the inner solar system. It would be a darned difficult piece of scientific sleuthing.

Despite the weakness on paleontology, this is a good read. I’m convinced, as I was before, that there is no other life in the universe that matches human intelligence. Most critics of this book seem to latch on to the notion that somewhere out there, there’s somebody else. I would be happy if they found people. But I’m not banking on it.

In a similar vein I also enjoyed Dimitar Sasselov’s The Life of Super-Earths. This volume starts in the 1990′s, and chronicles briefly the discovery of planets outside the solar system, and the gradual fine-tuning of our discovery sieve to the point where we can identify planets larger than Earth, yet smaller than Neptune. Hence the term, super-earth.

Dr Sasselov has had a part in these astronomical discoveries of the past two decades, so that personal touch makes this book a bit more engaging. And like modern astronomers, he draws on many disciplines like cellular biology, geophysics, and chemistry to offer his readers a more complete canvas of this scientific frontier.

We will eventually find Earth-sized planets. They may well harbor life. I think it more likely they will be locales for very interesting chemistry and geology. That is still a good reason to explore them.

To the lay reader, each of these books is engaging and readable. Read them quick, because the rapid pace of science these days may render some of the details incorrect, or at best, incomplete in just a few years.

 

Close Conjunction

From the skies of Earth, Jupiter and Venus will have their closest association tomorrow, appearing just a few degrees apart. Actual separation is more than 400 million miles.

But it made me think about even closer encounters in the sky. Don’t forget Venus transits the sun later this year, in June. (2004′s imaged, right) What about a planet transiting another planet? Does that ever happen? Sure does. Last time was 1818. But we’ve got a long wait for the next one. In fifty-three years, the brightest two planets will appear to merge in the sky, and Venus, through a telescope, will appear to cross the face of Jupiter as seen from Earth.

Something in my lifetime will be the December 2020 encounter of Jupiter and Saturn. They will appear to merge in the sky. In a small telescope’s view, you’ll be able to see two planets and five moons.