Charles Darwin, author of On the Origin of Species and father of the theory of evolution, was born on February 12, 1809, and published his book sharing his theory with the world fifty years later, in 1859.
Biologists and science geeks like me remember his birthday as Darwin Day every year.
Thirty-six light years across and still growing, it was born in fire and wind about 20,000 light years from earth when a star exploded and sent dust and gas flying through the galaxy at tremendous speed. Some 1,500 or 2,000 years later, the Chandra X-ray Observatory captured this beautifully detailed image and released it to the public on October 23, 2007. This is the Chandra G292.0+1.8 supernova remnant, located in our galaxy, in the constellation Centaurus.
Constellations like Centaurus aren’t real clusters of stars. They are really unrelated stars at different distances from earth that just happen to look close together. This group of unrelated stars looked to some of our ancestors as if they outlined a centaur, a legendary creature said to be half human and half horse, so they called the constellation Centaurus. Apparently, they had great imaginations!
But galaxies are real clumps of stars. Huge swirling clumps of different shapes containing billions of stars each. The Milky Way is a pinwheel-shaped galaxy 100,000 light years across, known as a spiral galaxy. We can’t take a picture of the whole Milky Way, because we live inside it; but it would look very much like the NGC 6744 galaxy shown here. Spectacular!
There isn’t enough time in an astronomer’s life to count that many stars. Besides that, many stars are hidden behind clouds of gas and dust. But various estimates are that our galaxy, the Milky Way, contains between 100 billion and a trillion stars. (The most common estimate seems to be about 200 billion, or 200,000,000,000 stars.)
You couldn’t count that many stars if you lived 1,000 years! Even if you COULD see them all from earth.
Anway, Chandra G292.0+1.8 is physically located in our Milky Way galaxy, in the direction of Centaurus. This beautifully detailed Chandra composite shows the rapidly expanding shell of gas formed by the explosion.
A pulsar located slightly below and to the left of the center is believed to be the star that exploded to form the nebula. While it would normally have been at the center of the remnant, recoil from the lopsided explosion may have kicked the pulsar in this direction.
The long white line running from left to right across the center is called the equatorial belt, and was probably formed when the star expelled material from around its equator shortly before it died.
Our universe is filled with incredible violence and chaos, but it produces some of the most beautiful and fascinating structures we can imagine.
Today is Asteroid Day, the 108th anniversary of the “Tunguska Event,” the largest asteroid impact in recorded history, when a roughly 40 meter-wide (125 feet) rock exploded high in the air over Tunguska, Siberia, in 1908. The explosion released the power of 185 Hiroshima-type atomic bombs (though without the deadly radioactivity) and flattened trees for many miles.
An asteroid, also known as a “meteoroid,” is simply a chunk of rock or iron shooting through space, usually in an orbit around the sun. Most of them, including the very largest, orbit in the so-called “asteroid belt” between Mars and Jupiter; but a relative few wander the solar system in essentially all kinds of possible orbits. And a “relative few” can be a very large number when we’re talking about asteroids.
Fortunately, there were no known human casualties of the Tunguska Event because the area was uninhabited. It was even several years before scientists could even get to the site to see what had happened.
Asteroid Day was designated, beginning last year, as a way to educate people about the danger imposed by near-earth asteroids. The more people who understand the danger, the more likely our leaders will be to put resources into finding ways to prevent it.
The Panoramic Survey Telescope in Hawaii is dedicated to finding asteroids that cross earth’s orbit, called “earth crossers” or “near earth asteroids,” because some of them could pose serious dangers to us. So far, it has found 10,000 of them and astronomers estimate there are literally several million more. The 10,000th one, found June 18, 2013, and designated Asteroid 2013 MZ5, was 1,000 feet (300 meters) across. If it were to strike our planet, it could unleash more than 400 times as much destructive power as the Tunguska Event. Fortunately, it’s path does not directly intersect with ours for the foreseeable future.
However, it was only four months earlier, on February 15, 2013, that the Chelyabinsk Meteor entered Earth’s atmosphere over the southern Ural region of Russia with a speed of approximately 19 kilometres per second (41,000 mph). Its light was brighter than the Sun, and it was visible up to 100 km (60 mi) away. Some witnesses even felt intense heat from the fireball.
The explosion shattered windows and did other damage, injuring at least 1,500 people enough to seek medical help.
This was a small one, and it approached earth from he direction of the sun, making it difficult to see. For these reasons, nobody knew it was coming until it streaked across the skies of Chelyabinsk.
Bigger ones are out there. They’ve hit our planet before, but it’s usually hard to find the craters because they’ve been destroyed or hidden by erosion. It’s easier to see that the moon is covered with craters from the bombardment it receives. Earth gets the same punishment from the sky, but the atmosphere burns up the small ones and soon degrades the craters the big ones leave.
The asteroid that finished off the dinosaurs 66 million years ago left a crater more than 180 kilometers (110 miles) in diameter and 20 km (12 mi) deep near Chicxulub, Mexico; but it is mostly under water. The asteroid itself was at least 10 km (6 mi) in diameter.
Possibly the best preserved asteroid crater is Meteor Crater, 37 miles (60 km) east of Flagstaff, Arizona. It is smaller, approximately 1.2 k (3/4 mi) in diameter and 170 m (560 ft) deep, as seen below, and was formed by a nickel-iron meteorite about 50 meters (160 feet) across about 50,000 years ago. It was about 50 m (160 ft) deeper before it eroded.
It’s easy to see that an asteroid this size could wipe out a small city and wreak havoc on a much larger area. Fortunately, there were no humans in North America that long ago; but it could happen just as easily today.
The Tunguska Asteroid could have destroyed a state or a small country.
The dinosaurs could not help themselves, but we can. By finding the rest of the asteroids that might endanger our planet, we can know when the next one is coming and where it will strike before it gets here.
Using modern space technologies we can deflect an asteroid endangering the earth before it gets here and save ourselves. But it requires resources to locate the dangerous ones and design, build, and test the protection.
Remind our national leaders, we don’t want to go the way of the dinosaur.
Here’s a nice video I found about evidences of evolution that you can see in your own body.
The Youtube page says it’s “Proof of evolution that you can find on your body,” but that’s too strong. Most scientists are hesitant to use the word “proof” about anything except math. While it’s easy to prove that 2+3=5, for example, it’s much more difficult to be absolutely certain about most other things. So let’s call these things “evidences” instead of “proofs.”
This is largely a philosophical distinction, of course. Even though it’s impossible to absolutely prove that all life on earth descended from a common ancestor, there is such an overwhelming amount of evidence that we should and do consider it a fact. It’s one of those cases of keeping an open mind, but not so open your brains fall out.
The little evidences discussed here are interesting because we can see them on our own skin. What’s totally convincing, though, is the massive amounts of evidence from the fossils, the genes and other chemistry of our bodies, viruses that invaded the genomes of our ancestor species and still exist in our own genomes as well as those of our cousin species, the ways living things have been and are distributed on earth through time and space, and many other lines of evidence that all agree with each other perfectly. Any part of it would be suggestive of evolution; but all together, it becomes incontrovertible.
I mean that literally, by the way. It is sometimes claimed there is a great controversy about evolution and that evolution is “a theory in trouble.” This is not true.
Any controversy is from amateurs, not biologists. Among scientists, there is almost universal agreement. Recent surveys have shown that over 97% of all scientists believe evolution is a fact. When the surveys included only biologists and scientists in closely related fields, the level of agreement rose to well over 99%.
Before you swat that next mosquito, remember — she’s your distant cousin! Then go ahead and swat her anyway. Those things carry disease germs. Which are your even more distant cousins, of course.
We usually don’t like that side of the family very much!
In our terrestrial view of things, the speed of light seems incredibly fast. But as soon as you view it against the vast distances of the universe, it’s unfortunately very slow. This animation illustrates, in realtime, the journey of a photon of light emitted from the surface of the sun and traveling across a portion of the solar system, from a human perspective.
I’ve taken liberties with certain things like the alignment of planets and asteroids, as well as ignoring the laws of relativity concerning what a photon actually “sees” or how time is experienced at the speed of light, but overall I’ve kept the size and distances of all the objects as accurate as possible. I also decided to end the animation just past Jupiter as I wanted to keep the running length below an hour.
You’re riding on a photon, a single “particle” of light.
You leave the sun’s surface, flying away at (naturally) the speed of light, or approximately 186,000 miles/second (299,792,458 meters/second).
You’ll cross the orbits of Mercury and Venus. After 8 minutes 17 seconds, you’ll finally cross the orbit of earth and begin heading toward Mars. By the time your first hour has gone, you’ll have flown almost seven billion miles. Far past mighty Jupiter and heading toward Saturn.
The hour-long video ends with you heading for Saturn, Uranus, Neptune, and the stars.
Here’s what you see as you look backwards toward the sun, getting farther and farther away.
Sun and planets, to scale. But the distances between them are not.
We’ve all seen the numbers that describe the solar system, and we can understand them with graphics like the two in this post. Earth has a diameter of about 8,000 miles, but the moon is only about 2,000 miles across. Jupiter, on the other hand, is about 84,000 miles across; and the sun is a whopping 836,000 miles in diameter.
These huge numbers are all rounded to the nearest thousand to make them easier to visualize. We can easily see that Jupiter is more than ten times the diameter of earth; and the sun, more than 100 times. The moon (not shown) is smaller, being only about a quarter of earth’s diameter.
Venus is almost as large as earth, but Mars is smaller, and Mercury is smaller still. At 70,000 miles, Saturn is a little smaller than Jupiter; and Uranus and Neptune are considerably smaller, but still far larger than earth.
Did I get you confused yet? No? Good. It’s really not hard. These number are big, but barely of a size range we can visualize.
What’s hard is picturing the distances between these objects. We don’t usually see them because they are too vast to fit on a screen or page. If we do see the space, the planets will be microscopic. What’s worse is that these distances between the objects are so huge it’s impossible for us to visualize them.
Consider these approximate distances from the sun:
Mercury: 36,000,000 (35 million miles)
Venus: 67,000,000 (67 million miles)
Earth: 93,000,000 (93 million miles)
Mars: 142,000,000 (142 million miles)
Jupiter: 484,000,000 (484 million miles)
Saturn: 889,000,000 (889 million miles)
Uranus: 1,800,000,000 (1.8 billion miles)
Neptune: 2,800,000,000 (2.8 billion miles)
Pluto: 3,700,000,000 (3.7 billion miles)
Sedna: 7, 100,000,000 to 87,000,000,000 (7.1 billion mi to 87 billion mi)
Yeah, I know Pluto isn’t a planet; but it’s still part of our solar system. So is Sedna. It’s a minor planet so small and so far away it wasn’t even discovered until 2001. It has a highly elliptical orbit way out beyond the orbits of the major solar system bodies. (Sedna has the red orbit in the picture; Pluto has the outer pink one. [Wikipedia calls it purple.] All the planets are crammed inside.)
Like the diameters of the planets, these numbers are also approximate. Since planetary orbits are not exactly circular, they represent the approximate average orbit of each planet.
At the far end of its orbit, Sedna is so incredibly far away it would take more than 141,000 years to drive that distance at 70 mph non-stop.
The objects in both pictures are drawn to scale, but the spacing obviously is not.
Here’s a video that actually shows the distances between the objects in the solar system TO SCALE. I’m sorry I can’t embed it, so you’ll have to click the link if you want to see it. Please do! It’ll be worth your effort.
This video shows the real size of the solar system by, in effect, placing 1,074 screens side by side. If you could print it out at 300 dpi, the paper would have to be 475 feet wide and earth would be invisible.
You’ll find the sun on the left and scroll right to find everything else. The scale is that our moon is one pixel. It’ the smallest dot possible on your screen. So earth is about 4 pixels across; still a very small dot. And everything else is to scale. Including the empty spaces between objects.
Get prepared for a LOT of empty space. It’ll blow your mind!
It’s from social media, Facebook in this case; so I can’t guarantee it’s legitimate. But it looks real to me. Still, science depends on skepticism, so we have to ask a few questions.
How did the swans get so tangled up in the first place? Is that even possible? Were they fighting? Or trying some fancy new sex positions? (That would be interesting in itself.) Could somebody have done this to them? Maybe to stage a photo op?
How did they know the guy would help them and not have them for dinner? Is is possible they were the guy’s pets? Or maybe they were so desperate they took a chance?
But how did they . . . how could they even decide together to trust the guy and swim to him for help, since swans don’t talk? Don’t they seem to be cooperating to swim to him? Is that possible?
I don’t know the answers to any of these questions, so this is really more about human interest than science. But it’s at least interesting and thought provoking.
Science starts with observations and questions. We’ve observed what appears to be two swans that needed help, so they seemed to come to a man for that help. If we were doing real science,we’d have to try to find out the answers to our questions first of all.
Then, depending on the answers, we might form a hypothesis that the swans actually agreed together to come to a man they knew nothing of to get help.
But, based on what really know about birds, that seems pretty unlikely. As much as I would like for this hypothesis to be true, it actually seems pretty unlikely.
Seeing is believing? Not really. Not until you’ve verified all the relevant information.
Charles Darwin, the Father of Modern Biology, was born on this date in 1809. If here were still alive, he would be 207 years old today.
It was he, along with a younger naturalist named Alfred Russel Wallace, who gave us the theory of natural selection that explains how biological evolution produces all the wonderful and terrible forms of life on our planet.
In his massive 1859 book, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, often shortened to On the Origin of Species, he first accumulated overwhelming amounts of evidence for the evolution of life.
Then he postulated that all living organisms had descended from “a few forms or … one” original ancestors and proposed natural selection as the mechanism.
Darwin got a lot of things wrong, of course. Genes hadn’t even been discovered yet. Mendel was doing his work in another part of the world about the same time, but Darwin evidently knew nothing of it. Regardless, Mendel’s work was not commonly accepted for another half-century.
The amazing thing is how much he got right!
He was not the first to realize species descend from other species. His own grandfather, Erasmus Darwin, among others, had already speculated about that. But Charles compiled such overwhelming evidence it became difficult for educated people to doubt it any longer.
Only then did he explain, for the first time, how it could have happened through a process he called “natural selection.”
Natural selection is, at heart, a very simple process. Darwin’s friend, Thomas Henry Huxley, exclaimed, “How extremely stupid not to have thought of that!” But nobody had.
That’s the way obvious things are. They are only obvious after somebody thinks of them.
In 1973, evolutionary biologist Theodosius Dobzhansky penned that “nothing in biology makes sense except in the light of evolution,” because it has brought to light the relations of what first seemed disjointed facts in natural history into a coherent explanatory body of knowledge that describes and predicts many observable facts about life on this planet.
“the single best idea anyone has ever had”
Still later, philosopher Daniel Dennett gave Darwin the prize for best idea ever:
Let me lay my cards on the table. If I were to give an award for the single best idea anyone has ever had, I’d give it to Darwin, ahead of Newton and Einstein and everyone else. In a single stroke, the idea of evolution by natural selection unifies the realm of life, meaning, and purpose with the realm of space and time, cause and effect, mechanism and physical law.
Dan Dennett, in Darwin’s Dangerous Idea
Scientists today almost universally accept evolution as the best explanation of the diversity of life on earth.
The great man summarized his theory wonderfully:
It is interesting to contemplate an entangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us.
. . .
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
Charles Darwin Origin of Species