Among fossils: How very old things remind us of our youth

The earth is 4.54 billion years old. That’s a big number to wrap your head around. Spending time among very old things helps, but even then it’s easy to forget that not only the fossils themselves are ancient; so is the rock they came out of, the planet circling a sun that has been around a long time.

Since my childhood, dinosaurs have arrested my imagination like nothing else in science, and what better place to witness the majesty of these ancient animals than the Houston Museum of Natural Science, displaying some of the oldest things on Earth? When I walk through the Morian Hall of Paleontology, I see the bones of creatures that lived millions of years ago, preserved naturally by the processes of geology, like mummies, but embalmed by mud, pressure, and minerals. These aren’t bones, really. They’re rocks, no different from petrified wood or the crystals in the Cullen Hall of Gems and Minerals. They were once creatures of flesh and bone, but the organic molecules and chemicals that made up their bodies, if they didn’t decay, were replaced atom by atom while the rest of life on Earth developed.


Lane, the most complete fossil specimen of Triceratops in the world. 65 million years old.

Mine is a problem of scope, I think. It’s a strange feeling to understand that Lane the Triceratops, the most complete specimen of this dinosaur, was under our feet during the fall of the Roman Empire, was still buried in the time of King Tutanhkamen, and remained undiscovered while Shakespeare wrote his sonnets. This animal died, and life went on as it always does. Its life among presumably millions of others like it was common. Undistinguished. But that specimen is no longer a Triceratops; it’s a skeleton made of rock. Not even a skeleton, but an impression of it. A three-dimensional photograph dug out of the album that is the many-layered dirt of our planet. This animal has become a symbol of history. Now that is rare.


Icthyosaurus mother. At least 146 million years old.

It’s remarkable, this action of preservation that the Earth is capable of. And it’s remarkable that we have developed the science to identify and understand these stones. We had to consider both the life cycle of rock and the taxonomy of life before we could begin to speculate what these samples could mean. But really, so what? They’re just rocks.

It’s the feeling of humility they deliver that makes them fascinating. It’s like walking through modern Rome after living in developing Houston, surrounded by buildings a thousand years old that stood before the United States was even imagined. We’ve been walking around these seven continents for millenia, in the dark about what was under our feet until the birth of paleontology in 1666, when Nicholas Steno identified “tongue stones,” known then only as triangular rocks, as fossilized shark teeth. Dinosaurs were around whether we knew they existed or not. They are as old as the rock we walk on.

Icthyosaur Baby

Impressions of Icthyosaurus pups in the rib cage of this rare specimen suggest this animal died in childbirth.

Now consider this. In 2011, biologists identified 20,000 new species, a large number of them beetles, and most of them invertabrates. That was in a single year. Now take that diversity and multiply it by the age of the Earth. I’m not going to do the math, but that’s the number of species paleontologists have yet to discover. That’s the amount of life we potentially have yet to search for in the rock.

After early hominids, fossils of the first humans date back 1.8 million years, along with mammoths, mastodons, and saber-toothed cats that appear in the rock alongside them. Triceratops lived in the late Cretaceous, discovered in rock at least 65 million years old. Icthyosaurus swam the oceans and gave birth to her young between 245 and 146 million years ago, in the Jurassic and the Triassic. (Their era lasted 100 million years. Again, we’ve been around for 1.8.) Trilobites in our collection have been preserved for between 540 and 360 million years, and the stromatolites, layered rocks formed by ancient bacteria, date back to 3.4 billion years. Not million. Billion. They appeared in the Archaeozoic Eon, about a billion years after Earth solidified out of molten space-rock.


One of the best preserved and most intricate trilobites in the world. At least 360 million years old.

What will the occupants of this planet find after the next million years? We’ve been around for a while, but not nearly as long as these fossils. What will paleontologists of the future, if they still exist, find in another 65 million years? 146? 540? 3.4 billion? The Earth will still be here by then; humanity is another story. Will we still cling to the crags in a different form, the maps unrecognizeable to the once-dominant species of 2015 CE, if they could see them? Will we have preserved our history as well as the rocks have preserved the dinosaurs?


Stromatolite formed by layers of ancient bacteria preserved in rock. At least 3.4 billion years old.

In another 3.4 billion years, the sun will be nearing the end of its life, having expanded into a red giant and swallowed Mercury and Venus. According to many estimations, by the time the sun is 7.59 billion years old, it will engulf the Earth. We are living in our planet’s middle age. It took half the Earth’s life for humanity to arise and build its cities. For the United States to claim its sovereignty.


Lucy, Australopithecus afarensis, the most complete skeleton of this hominid in the world. 3.18 million years old.

The Earth is old, dude! We never pay this age any mind until we identify something to date it against. Here we have Triceratops, say, a creature that lived in the time when this rock was young, just a pile of sediment on the floor of the ocean or a river. Paleontologists owe a lot to the power of speculation and theory. We may never know for sure what life was like in the era of these ancient creatures. But if we have anything in common with the dinosaurs, ancient mollusks and archaebacteria, it’s that we all grew on this same rock.

In a way, we’re just as old as they are. Our bodies are made up of the same elements that have always been here in some form or another, buried under the crust in a molten mantle, or exposed to the light of the sun that has fueled life on Earth for as far back as the imagination will stretch. As Carl Sagan said, “We are all made of star stuff.”

Science Starts with density and distance

A rousing game of “Will it Float?” occasionally played on The Late Show with David Letterman was really just an impressively popular density guessing game. In our recently added Science Start Outreach Program, Discovering Density, we play a similar game, predicting and testing to see what happens when you toss things into a tank of water. The Science Start program is for grades K-2 and travels to schools, daycares, scout groups, and more to educate students with hands-on learning experiences. 


Sahil tests the hypothesis that a tiny metal car is denser than water and will sink.

The most fun results are the ones that surprise the young students, like a whiffle ball that will not sink even though it is full of holes, a Lego brick (you’ll have to test that one out for yourself), or liquids that can float on or sink through other liquids in a density column.


Carolyn points out to a class at Passmore Elementary that an object that is floating must be touching the surface of the water in a presentation of the new Discovering Density program.

Making the distinction that density isn’t just about weight or mass or size but instead the comparison between the two can be a tricky concept at first. Similarly, very small and very large numbers, distances, and time scales can be difficult to grasp, so to make it a little easier, you could try holding a planet like Jupiter or maybe Neptune, if you prefer, as we model the vast distances of our solar system and think about scale in Space: Going the Distance.


Carolyn points out the different types of liquids forming four distinct layers in the density column that she made during the presentation. The density column was given to the group’s teacher after the show so that students could watch it change over time.

Volunteers spread out with their planets to see the relative spaces between their orbits and explore what a model is, why it’s helpful, and what about the model isn’t quite as it is in real life. For our model to be to scale for both the sizes of the planets and for the distances between them is tricky—in a classroom-sized solar system, it’s going to be almost impossible to see most of the planets from most seats, and even the sun seems petite!


Carolyn holds up a three-foot board that models the planet Jupiter. If Jupiter was just three feet across, the Sun would have to have a diameter of 23 feet!

Book Science Start for your school or scout group today by contacting Greta Brannan at (713) 639-4758 or For more information on HMNS outreach programs, click here.

Ride on a Shooting Star: Space Fuel

After the decimation suffered during World War II, mankind took a look at all the new technologies he had created to fight the war and turned his gaze towards the stars. From the late 1940’s this onward and upward reach has helped to fuel the engines of our ingenuity, but what has fueled those stellar ambassadors that now dot our solar system and beyond.

654 - Galaxies - Seamless Texture
Creative Commons License photo credit: Patrick Hoesly

To move from the surface of the earth to this new ocean a rocket must be moving about 7 miles per second. That takes a lot of energy. Many different propellants have been used. The very first rocket fuels were a mix of kerosene and liquid oxygen. Alcohol, hydrogen peroxide, and liquid hydrogen have also been used, in addition to solid fuels. They can provide thrust without the need for all the refrigeration and containment equipment that some of the liquid fuels, such as liquid hydrogen and oxygen, require.

Once the probe is beyond the reach of the atmosphere there is no way to change what’s on board.

The probe cannot drop by the local Radio Shack and pick up a fresh pair of AA batteries. While the probe is being built on Earth, the engineers must make sure that they provide a source of power that will give the probe the right amount of power.

Too little power and the scientific instrumentation won’t work; too much power could over heat the probe. On board chemical batteries can be used, but they take space that could be used for scientific instruments. Solar panels can be used, but only up to a certain distance from the sun. Beyond the orbit of Jupiter, probes need an internal power supply that will last for years.

They use the heat from radioactive decay of fissionable isotope.

Sputnik 1 in Orbit Sep 10-4-57
Creative Commons License photo credit: FlyingSinger

Early probes like Sputnik and Explorer 1 used chemical batteries to power their systems. In March of 1958 Vanguard 1, the 4th artificial satellite and the 1st powered by solar power, was launched. Probes with solar panels have more space on board for scientific instruments than probes that use only chemical batteries. Probes sent into the inner solar system (sun to Mars) are almost all powered using solar arrays.

Mariner 2, the first USA probe to Venus, suffered the loss of one of its solar arrays, but because it was closer to the sun, it was able to operate using only one solar array. No American manned space craft have made use of solar arrays yet (the new Multi-Purpose Crew Vehicle may), the Russian Soyuz spacecraft have used them since 1967.

The International Space Station (ISS) is the largest man-made structure outside our atmosphere.

Larger than a football field (but smaller than a football pitch), this outpost orbits the earth every hour and a half. It is also powered completely by solar power. Past the atmosphere, solar power becomes more practical and more consistent (there is no night in space). Because of the orbital path of the ISS, it is eclipsed by the earth for 30 minutes out of every hour and a half. The station makes use of rechargeable batteries to make sure it is never without power.

From a Distance
Creative Commons License photo credit: Undertow851

As the probes go farther and farther away from the sun, the light that can reach them is less and less.

Until August of 2011, no probe to Jupiter had ever been powered just by solar panels. Juno, the latest probe to Jupiter, has the largest solar arrays given to a deep space probe and the first probe to Jupiter to use solar arrays.

Jupiter receives only 4% of the sunlight we enjoy on Earth. Advances in solar technology have now made it practical to use solar panels out 5 Astronomical Units (AUs) from the sun. All other deep space probes have used a radioisotope thermoelectric generator (RTG).

A RTG works by converting the heat from the decay of a radioactive fuel into electricity. American probes have been using Plutonium 238 (an isotope of Plutonium) since the late 1960’s. It has a half life of about 88 years. RTGs have powered all our interplanetary probes (the Voyagers and Pioneers and soon to be New Horizons). However, NASA has begun to run out of fuel for the RTGs and the creation of more is full of political and safety considerations.

There he goes, after an all day long work.
Creative Commons License photo credit: giumaiolini

The technology that we’ve made to go out to the ‘verse with will also help us here on the cool, green hills of earth. RGTs have been used, mainly by Russia, to provide power for off the grid light houses. Advances in solar panels for space are used down here on Terre Firma. With the reliably of solar power in space, there are even attempts to construct orbital solar collectors to beam down electricity. There will be from heaven to Earth more than is dreamt of.

Go Stargazing! August Edition

Saturn is the only planet visible to the naked eye at night this August.  Face southwest at dusk and you’ll see Saturn near a star of similar brightness—Spica in Virgo.  Saturn is a bit to the right of Spica as you face southwest.   The ringed planet remains well placed for evening viewing and remains in the night sky until late September 2011.

Hubble Images Suggest Rogue Asteroid Smacked Jupiter
Creative Commons License photo credit: NASA Goddard Photo and Video

Mars and Jupiter are in the pre-dawn sky.  Jupiter, set against a background of very dim stars, dominates the southeastern pre-dawn sky and is due south at dawn by the end of the month.  Mars is dimmer and much lower in the east northeast.  It has fully emerged from the sun’s glare and will brighten slightly each morning. Venus is now out of sight.  Superior conjunction (alignment on the far side of the sun) is on August 16.

The Big Dipper is to the left of the North Star, with its handle pointing up.  From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are in the west and southwest at dusk.  Antares, brightest star of Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to its left.  Meanwhile, the Summer Triangle is approaching the zenith.  The stars of summer now dominate the evening sky.  In late evening, you can watch the Great Square of Pegasus rise in the east.

Moon Phases in August 2011:

1st Quarter                     August 6, 6:08 a.m.

Full Moon                       August 13, 1:57 p.m.

Last Quarter                  August 21, 4:56 a.m.

New Moon                      August 28, 10:03 p.m.

The annual Perseid Meteor Shower peaks this year on Saturday morning, August 13.  Unfortunately, the moon (full on the 13th) hides all but the very brightest meteors and thus spoils the show.  If you want to see just how many Perseids can outshine the moonlight, the best hours are from roughly 2 a.m. to dawn.