Gold on Earth Owes Its Existence to Dwarf Galaxy Mergers

 Our Milky Way galaxy, like all large galaxies, grew by accreting many smaller galaxies billions of years ago. And, you or your spouse’s, wedding ring owe those galaxies a debt of gratitude.

When our universe first came into existence nearly 14 billion years ago, it contained only hydrogen, helium, and a trace amount of lithium. These are the three lightest and simplest elements. A glance at a periodic table shows our universe contains 92 naturally occurring elements with uranium being the heaviest. We have created another dozen or so elements in laboratories around the world. Of those 92, all of them up to iron are created inside normal stars, like our sun.

Stars form these heavier elements through a process called nuclear fusion. The incredible heat in a star’s core slams lighter elements together making heavier and heavier elements and releasing more energy into the star’s core. But making iron requires more energy than it creates. Fusion reactions almost instantly halt.

Stars like our sun die rather quietly after that point. But, stars more than ten times larger than the sun die in a spectacular supernova explosion. These events release so much energy that elements heavier than iron can form. However, supernova explosions cannot account for the amount of “jewelry store elements,” like gold and platinum, in the universe.

Recent studies revealed that collisions between two neutron stars release enough energy to create the amount of gold in the universe. Astronomers have discovered hundreds of gold-rich stars in the Milky Way. But they wanted to know when and where these stars formed. Scientists from Notre Dame and Tohoku University in Japan used a powerful supercomputer to run simulations. Their work showed these stars formed in dwarf galaxies that merged with the Milky Way some ten billion years ago. In their study, they said “The gold-rich stars (we see) today tell us the history of the Milky Way. We found most gold-rich stars are formed in dwarf galaxies over 10 billion years ago. These ancient galaxies are the building blocks of the Milky Way.”

Colliding neutron stars. Credit NSF-LIGO-Sonoma State Unioversity-A. Simonnet

Not only did these many dwarf galaxies grow our Milky Way, they also created most of the gold that exists on Earth. The universe does work in mysterious ways.

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Did an Alien Race Signal Us?

 Astronomer Frank Drake first pointed a radio telescope toward the skies in 1960 in a deliberate search for alien signals, and SETI, the search for extraterrestrial intelligence, began. Since then, astronomers have spent many thousands of hours searching for alien signals.

In 1965, Ohio State University built the Big Ear radio telescope specifically to search for alien transmissions. On the night of August 15, 1977, astronomers ran an automated scanning program in a region of the constellation Sagittarius. At 10:16 p.m., the telescope detected a 72-second burst of radio noise in the frequency range astronomers thought the best to search for alien signals. The next morning, astronomer Jerry Ehman reviewed the computer log and noticed a signal that was 20 times stronger than the background noise. He circled that portion of the computer printout and wrote “Wow!” in the margin.

Although astronomers have repeatedly searched that area of the sky looking for a repeat of the Wow signal, it has never come again. Over the years since, astronomers hunted for any possible non-alien explanation for the signal without success. Recently, the director of the Habitable Exoplanet Hunting Project, Alberto Caballero, stated "The 'Wow!' signal is still considered the best SETI candidate radio signal.” He began a search of the region of the sky where the signal originated looking for likely candidate stars.

                                            The "Wow!" signal. Credit SETI Institute

He searched for stars similar to our sun in size, age, and brightness that might host Earth-like planets. He examined data collected by the European Space Agency’s Gaia mission which is creating a map of more than a billion stars with unparalleled precision. He found 66 candidate stars similar to our sun.

Astronomers must now examine those stars to see if any possess Earth-like planets orbiting them. This process may take a while, but if the Wow signal came from an alien race, this may be our best chance to discover another intelligent civilization. At such great distances to these stars, back-and-forth communication may be impossible. But, at least we’d know we’re not alone in the universe.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Is there Life on Another World in Our Solar System?

       Life on Earth takes a bewildering, almost unimaginable range of forms. Some seem so different, it’s hard to believe they didn’t evolve on an alien planet. One resource all life on our planet requires to survive is water. Most scientists, therefore, believe that if we are to find life elsewhere, we must find a planet or moon with sufficient liquid water.

As it turns out, water is not scarce in the universe. It is a compound of atoms of hydrogen and oxygen, which are the first and third most abundant elements in the universe, making water, H2O, one of the most abundant substances in the universe.

The problem is finding water in a liquid form. On many alien planets we have discovered, the temperature is so hot that the water is all in vapor form. Or it might be underground and, perhaps, too salty to support life as we know it.

One example is Saturn’s moon Enceladus. NASA’s Cassini mission discovered jets of water spewing off the tiny moon. That really surprised scientists. They thought that moon was so small that any water would be frozen solid. But the action of Saturn’s gravity on the moon warms it up enough that Enceladus possesses a global, underground liquid water ocean. Originally, scientists assumed it might be far too salty to support life.

Water Jets spewing into space from the South Pole region of Saturn's moon Enceladus. 

Credit NASA-JPL-Space Sciences Institute

A group of researchers at MIT decided to work on a project to determine if that water could support life. They discovered that the thickness of the polar ice shell is dependent on the water’s salinity. Their analysis of data showed that the ice on the moon is thinner at the poles than at the equator. They determined that the salinity of Enceladus’ ocean is lower than that of Earth’s oceans. And Earth’s oceans contain lots of life.

Cut-away view of the ocean on Enceladus. 

Credit NASA-JPL-CalTech-Southwest Research Institute

That doesn’t automatically mean that Enceladus has life in its oceans. Other factors also determine habitability. But at least the water on the moon can support life. That dramatically increases the odds of extraterrestrial life there.

 

Each month, I write an astronomy-related column article for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

 This is reprinted by permission from the Oklahoman and www.Oklahoman.com.

Will We Recognize Intelligent Aliens when We Meet Them?

 Science fiction depicts many types of intelligent aliens. Often they are similar to humans, but with different, often bizarre, heads. However, most biologists believe that any aliens are unlikely to resemble humans at all. Life evolves due to the environmental conditions of the planet, and it is extremely unlikely that any other planet will have a geological and environmental history similar to Earth’s. With different conditions, intelligent life on those planets will take different forms compared to us humans.

Grey Aliens. Most commonly described by those who claim to have been abducted by aliens.

image by kjpargeter

But not all scientists agree with that idea. Simon Morris, a paleo-biologist with Cambridge University’s Department of Earth Sciences, believes, researchers that intelligent creatures similar to humans likely exist on many other planets.

Intelligent aliens are not likely to appear humanoid. From Star Trek Voyager

Non-humanoid alien. Created by Abiogenesis

Morris cites the theory of convergent evolution, which says intelligent species everywhere may evolve into something much like us. “One can say with reasonable confidence that the likelihood of something analogous to a human evolving is really pretty high. And given the number of potential planets that we now have good reason to think exist, even if the dice only come up the right way every 1 in 100 throws, that still leads to a very large number of intelligences scattered around, that are likely to be similar to us.”

As an example of this idea, Morris says that flight independently evolved at least four different times on Earth, in pterosaurs, birds, bats, and insects. Eyes, he says, evolved in different species perhaps as many as 40 times.

Many scientists strongly disagree with that idea. One of those is the late evolutionary biologist Stephen J Gould who found this idea utterly ridiculous. He claims that if you re-ran evolution on Earth, even given the same geological and environmental changes our planet endured, the likelihood of getting humans just like us is vanishingly remote. Since random environmental effects create random sets of genetic mutations, there is almost no possibility of ending up at the same evolutionary point. And imagining this evolution occurring on a distant planet with very different conditions compared to Earth is foolish.

Most scientists agree with Gould. And besides, if all intelligent life were just like, what a boring universe this would be.

  

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

This is reprinted by permission from the Oklahoman and www.Oklahoman.com.

Earth will be destroyed by our Sun

 Like everything else in nature, astronomical objects change and evolve in time. Take our sun, for instance. When it first formed, our sun slowly fused hydrogen into helium, just like a hydrogen bomb. As it aged, it became more compact which increased the rate of hydrogen fusion in its core. It now emits 30% more energy than when it first started starting fusing hydrogen.

As the hydrogen fuel is slowly consumed, the helium “ash” builds up in the core causing the hydrogen fusion area to move closer to the surface. This heats the surface of our star causing it to swell, making the sun expand. Eventually, our sun, as do all stars like it, will evolve into a red giant star, one hundred times larger than it is now.

Our sun as a red giant star, scorching Earth. Credit NASA.

At that point, our star’s surface will extend farther than Earth’s current orbit, swallowing Mercury and Venus, the planets closer to the sun than Earth. It’s not automatic that Earth will be consumed by the growing sun. As the sun grows, it blows off more and more material as solar wind. As the sun’s mass decreases, Earth will slip farther out. But even if Earth survives, and most astronomers think it won’t, our planet will become so hot that the oceans will boil and fires will consume all life on the planet.

Earth being destroyed by Red Giant sun. Credit NASA.

By studying the light spectrum of stars, astronomers can measure their chemical makeup. The chemical abundances of some stars in our galaxy at a more advanced stage of stellar evolution than our sun reveal that planets once orbiting that sun have been engulfed and destroyed in the fiery atmosphere of the star. They find elements in the star that can only have come from orbiting planets. They can see that these suns devour their planets as they age and grow larger, just as our sun will do one day.

Alien astronomers on other planets studying our solar system a few billion years in the future will be able to detect the remnants of Mercury and Venus. Will they also detect the remnants of Earth? We don’t yet know for sure, but we do that we humans will have either perished or moved out into space in search of Earth 2.0.

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

       This is reprinted by permission from the Oklahoman and www.Oklahoman.com.

Lunar Colonies: Water on the Moon and Growing Plants in Lunar Soil

 Traditional scientific thought says that our Moon is a dead world. The core is solid so no internal geological activity occurs. It has no atmosphere, water, or life. But, in the past, massive volcanic eruptions occurred on our natural satellite. These volcanoes created lava tubes large enough to hold a city. And, just as with volcanoes on Earth, lunar volcanoes belched out gases and water vapor creating a temporary atmosphere on the Moon. The Moon’s weak gravity couldn’t hold any atmosphere, and with daytime temperatures reaching more than 250 degrees, all the water belched from these volcanoes quickly evaporated into space.

With the help of orbiting satellites like the Lunar Reconnaissance Orbiter, scientists discovered cold traps, craters at the north and south poles of the Moon so deep that sunlight never reaches the crater floors. Some of the water vapor belched out by the volcanoes wanders around the lunar surface to freeze in these craters before the sun can boil it into space. Over the eons, ice sheets hundreds of feet thick have formed in these cold traps. Dust kicked up by the many meteors striking the Moon covers the ice, further insulating it from the daytime heat.

NASA plans to send astronauts back to the Moon within this decade with the Artemis mission. They plan to land at the Moon’s south pole. The water there can be used both for drinking and as a source of rocket fuel.

The Moon's North and South poles. Credit NASA.

Andrew Wilcoski, a doctoral student in the department of astrophysical and planetary sciences and the Laboratory for Atmospheric and Space Physics at CU Boulder, is the lead author of the study published in The Planetary Science Journal “We envision (the ice) as a frost on the moon that built up over time,” he said. “It’s possible that 5 or 10 meters (16 to 33 feet) below the surface, you have big sheets of ice.”

Just a few decades ago, no astronomer would have believed this was possible. Now, lunar ice will allow astronauts to stay for an extended time on the moon.

Another group of researchers at the University of Florida in Gainesville planted thale cress seeds in lunar soil returned by Apollo astronauts. Although the plants grew more slowly and were scrawnier than others grown in volcanic material from Earth, they did sprout and grow. “Nothing really compared to when we first saw the seedlings as they were sprouting in the lunar regolith,” says Anna-Lisa Paul, co-author of the study. “That was a moving experience, to be able to say that we’re watching the very first terrestrial organisms to grow in extraterrestrial materials, ever. And it was amazing. Just amazing.”

Plants grown in Lunar soil returned during Apollo missions. Credit Tyler Jones, IFAS, University of Florida

Lunar colonization seems closer than ever with these two studies. People now alive may well be the first inhabitants of a permanent lunar colony.

 

Each month, I write an astronomy-related column for the Oklahoman newspaper. On the following day, I post that same column to my blog page. 

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

James Webb Telescope Ready to Change Our Knowledge of the Universe

 Our most amazing astronomical photos come from the Hubble Space Telescope. Hubble launched into space to bring us these detailed photos that have changed our understanding of the universe over 30 years ago. Hubble’s successor is the James Webb Space Telescope, now fully deployed. The JWST stands poised to change our perspective of the universe yet again. JWST has a much greater collecting area than Hubble and a more sensitive detector.

Hublle Space Telescope's collecting mirror compared to JWST's main mirror. Credit NASA

The JWST may change our understanding of our place in the cosmos by studying extrasolar planets, planets orbiting other stars. On Earth, plants cover much of our land surface. NASA launched the Galileo mission to Jupiter in 1989. On the way there, the spacecraft took a look back at Earth and detected our planet, vegetation red edge (VRE) biosignature, the mixture of red and infrared light reflected by plants, a signal JWST could observe from exoplanets.

Any exoplanet that bears life will likely have large areas covered with forest- and prairie-like plants just as on Earth. JWST possesses the capability to detect the VRE signal from such planets. While extensive plant cover won’t necessarily indicate the presence of intelligent life, it proves that life on those planets has evolved beyond the simple, single-celled forms that alone populated Earth for a billion years.

JWST’s detectors are sensitive enough to identify another tell-tale sign of life on alien planets. When a planet moves in front of its star, the starlight passing through the planet’s atmosphere, if it has one, allows the telescope to determine what gasses make up that atmosphere. Oxygen is a very reactive element. It is easily used up in chemical processes, such as combining with iron-bearing rock to turn it red, which is common on Earth. Our planet maintains a large supply of oxygen in our atmosphere because it is constantly replenished by photosynthesizing plants.

Methane is also a gas that can’t remain long in a planet’s atmosphere. On Earth, many forms of life give off methane. Think of cows burping. So, if a planet has a steady supply of methane in its atmosphere that likely indicates the presence of life.

JWST’s greatest contribution to our understanding of the universe will undoubtedly come from detailed images of astronomical objects and phenomena, just as with Hubble. But finding proof of extraterrestrial life may well be the most exciting discovery made by the James Webb Space Telescope.

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. On the following day, I post that same column to my blog page.

 This is reprinted by permission from the Oklahoman and www.Oklahoman.com.