Dark Matter, Dark Energy and Normal Matter

Dark matter fascinates me and fascinates scientists, even we can't really prove it exists. 

Why do we think there is such a thing? Galaxies don’t rotate by the same physics that we know and understand. Scientists noticed that stars at a galaxy’s edge rotate faster than expected. 

How can we explain that? There must be matter that is invisible to us that is there. In 1998, the Hubble Space Telescope observations of a very distant supernova showed that a long time ago the universe was actually expanding more slowly than it is today. We once believed that gravity was causing the slowing expansion of the universe, but now that wasn't a certainty. 

 
Credit: NASA/STSci/Ann Feild[

The diagram above shows the rate of expansion since the universe's birth 15 billion years ago. The curve changes noticeably about 7.5 billion years ago, when objects in the universe began flying apart at a faster rate. Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart. 

Astronomers know more about what dark matter is not than what it actually is. Roughly 68% of the universe is dark energy, and dark matter makes up about 27%. The rest is everything on Earth. This "normal matter" is less than 5% of the universe. Actually, that hardly makes it qualify as the"norm."

Most of the universe is made up of dark energy, and that mysterious force drives the accelerating expansion of the universe. The next largest ingredient is dark matter. 

At one time, the theory was that MACHOs (Massive Compact Halo Objects) were the cause.  A MACHO, such as a brown dwarf star, would be so massive that it would bend light around them. We know they exist, and we know they are out there, even though they are too dark for us to see. But this theory fell out of favor because there are not enough of them to make the galaxy-rotation math work.

Astrophysicists next came up with the WIMP (Weakly Interacting Massive Particles - the scientists do have a sense of humor). Maybe the universe is full of very small things we can’t see.

And maybe dark matter is made up of a different object we have never observed. One candidate is the neutralino.

We keep looking. The Large Hadron Collider, one of the most expensive science experiments ever built, is looking, but hasn't found them. But we do know that the universe is "heavier" than what we can see.

"There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy," says Hamlet and that continues to be true. 

This month a TV series titled Dark Matter, based on the novel of the same name by Blake Crouch hits streaming service Apple+.

Dark matter and the expanding universe don't keep me up at night, but it did bother Alvy in the film Annie Hall.

Copernicus, the Universe and the Church

Astronomer Nicolaus Copernicus was born in Torun, Poland in 1473. He laid the foundation for modern astronomy by disputing the widely held belief that the Earth was the center of the universe. Instead, he pronounced that Earth, and the other planets, revolved around the Sun. This theory caused profound shock and a revolution in scientific and philosophical thought.

The Christian Church, Protestants, and Catholics alike believed that God had created the Universe just for mankind and so the Earth must be the center of it. That did not fit with what Copernicus knew about physics and the motion of the planets. With that belief, he couldn't make the math work or match his observations. He realized that if he created a new model and moved the Sun to the center, the equations all functioned much more smoothly.

Sometime between 1510 and 1514, Copernicus published his "Little Commentary" on his new model, a 40-page outline of his heliocentric — sun-centered — universe, which he sent to various astronomers while he continued working on a much longer, more detailed discussion of the idea. 

The expanded work was On the Revolutions (1543), which Copernicus dedicated to Pope Paul III, hoping the Pope would protect him from vilification for having removed the Earth from its sacred place. On the Revolutions hardly created a revolution when he wrote it; it was groundbreaking and controversial but, contrary to popular lore, the Church didn't immediately condemn him for it.

There were also those before Copernicus who had posited similar theories. Philolaus (c. 470 – c. 385 BCE) described an astronomical system in which a Central Fire (different from the Sun) occupied the center of the universe, and a counter-Earth, the Earth, Moon, the Sun itself, planets, and stars all revolved around it, in that order outward from the center.

Heraclides Ponticus (387–312 BCE) proposed that the Earth rotates on its axis. 

Aristarchus of Samos (c. 310 BCE – c. 230 BCE) was the first to advance a theory that the Earth orbited the Sun. Further mathematical details of Aristarchus's heliocentric system were worked out around 150 BCE by the Hellenistic astronomer Seleucus of Seleucia. Though Aristarchus's original text has been lost, a reference in Archimedes' book The Sand Reckoner (Archimedis Syracusani Arenarius & Dimensio Circuli) describes a work by Aristarchus in which he advanced the heliocentric model.

The Firsts of Johannes Kepler

The German astronomer Johannes Kepler was born to a father who was a poor mercenary in Württemberg, Germany in 1571. Kepler was nearly blind from a smallpox epidemic when he was three. That led to one of several "firsts" in his career. He developed the first eyeglass designs for nearsightedness and farsightedness. 

He was also the first to explain that the tides are caused by the moon.

He was the first to propose that the sun rotates on an axis.

He was the first to use planetary cycles to calculate the year of the birth of Jesus Christ.

Kepler also tracked the orbital path of Mars and published his three famous laws of planetary motion — which validated Copernicus’s theory of a sun-centered solar system — and later helped Isaac Newton discover the law of gravity. 

So, it is no surprise that if you hear his name today it is probably in the context of the Kepler Space Telescope and its search for exoplanets. It has found many more lanets than expected, including some of the smallest and ones that orbit more than one star.

Islands of Stars

Milky Way Galaxy

Until 1924,  the Milky Way galaxy - our galaxy - represented the entirety of the universe. That year, astronomer Edwin Hubble announced the discovery of other galaxies.

Hubble was studying the Andromeda Nebula at Mount Wilson observatory in California, — the most powerful telescope in the world at that time. He was able to to distinguish individual stars within the nebula.

One of the stars he observed is called a Cepheid variable. This is a type of star that pulsates and is very bright and that by observing and measuring its brightness and the length of time it takes to go from bright to dim and back again, one could calculate the star’s distance from the Earth. 

Hubble calculated that the star he was observing was 800 thousand light-years away, more than eight times the distance of the farthest star in the Milky Way, and so he realized that the “cloud of gas” he’d been observing was really another vast galaxy that was very far away. He renamed the Andromeda Nebula the Andromeda Galaxy.

Hubble would discover 23 more separate galaxies. Our Milky Way galaxy is just one of many little islands of stars.

Andromeda Galaxy

The Largest Black Hole and a Strange Brightness

The largest observed black hole to date is 10,000 times larger than the one at the heart of the Milky Way

First, astronomers reported that they found the largest black hole to date.

Next, they observed the supermassive black hole closest to Earth glowing with "unprecedented brightness."  Why? They're not sure.

The glowing black hole is known as Sagittarius A* (or Sgr A*). It is 4 million times as massive as the Sun and about 26,000 light-years from Earth. Think about that. Can you grasp that size? I can't and I doubt that you can either.

No visible light can escape the gravitational pull of a black hole, but on one night of observation it showed a brightness about twice as bright as the brightest measurement in the past 20 years.

In a wonderful understatement, Tuan Do, an associate research scientist and deputy director of the galactic center group at UCLA, who led the study, said "That indicates that perhaps something interesting is happening physically in the region of the black hole."

Interesting indeed.

Here's a timelapse of images over 2.5 hr from May from @keckobservatory of the supermassive black hole Sgr A*. The black hole is always variable, but this was the brightest we've seen in the infrared so far. It was probably even brighter before we started observing that night! pic.twitter.com/MwXioZ7twV

— Tuan Do (@quantumpenguin) August 11, 2019

Potential explanation: A star called SO-2 and another object called G2 got very close to Sgr A* in recent years, which could've ejected gas into the region that the black hole absorbed potentially causing the recent fireworks.

Mapping the Universe

From the first lunar atlas -1647

A lot of us think of mapping the universe as starting with people like Galileo and the invention of the telescope, but obviously we have ben looking to the heavens and, perhaps in crude ways, trying to put it down and record what we saw for a much longer time. This cataloging of the the heavens and making visible both what we see and later what we imagined was there or beyond is still going on, and I imagine it will continue well past all our lifetimes..

We know a lot now. This week NASAs' Juno spacecraft went into its orbit around Jupiter and we'll know even more. And yet we still have much to learn and discover.

Several articles on the www.brainpickings.org website ponted me to books about the ways we have imagined the shape and design of the uinverse. One of those is Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos by Yale theoretical astrophysicist Priyamvada Natarajan. Her premise is that the advent of modern cosmology and astrophysics is what has shaped our understanding of the universe and our place in it.

The book gets into the mapping of the invisible, such as black holes and dark matter, the accelerating expansion of the universe, the echo of the big bang, the discovery of exoplanets, and the possibility of other universes.

We are far beyond the earliest maps of the Sun and Moon and the attempt to describe why they - or was it the Earth? - was changing positions in the heavens.

The book and this kind of inquiry also reminds us that science will always be changing and incomplete, and that is a thing wonderful in the old full-of-wonder manner.

Astrophysics, say Natarajan, is using powerful tools to answer the same questions that our ancestors tried to answer through mythology:

Cosmology, perhaps more essentially than any other scientific discipline, has transformed not only our conception of the universe but also our place in it. This need to locate ourselves and explain natural phenomena seems primordial. Ancient creation myths shared striking similarities across cultures and helped humans deal with the uncertainty of violent natural phenomena. These supernatural explanations evoke a belief in an invisible and yet more powerful reality, and besides, they rely deeply on channeling our sense of wonder at the natural world. The complex human imagination enabled ancient civilizations to envision entities that were not immediately present but still felt real. Take for instance Enki, the Sumerian god of water whose wrath unleashed floods, or the Hindu god of rain and thunderstorms, Indra, whose bow was the rainbow stretched across the sky with a lightning bolt as his arrow. The most powerful myths are the ones that force us to take huge leaps of imagination but, at the same time, help us to remain rooted.

The Juno spacecraft entered orbit around Jupiter on the 4th of July this year (NASA/JPL-Caltech)

Watching the Milky Way

The Mountain from TSO Photography on Vimeo.

This was filmed between 4th and 11th April 2011 at El Teide, Spain´s highest mountain. It is one of the best places in the world to photograph the stars and is also the location of Teide Observatories, considered to be one of the world´s best observatories.

The goal was to capture the Milky Way galaxy along with El Teide but a large sandstorm hit the Sahara Desert on the 9th April and then hit El Teide making it nearly impossible to see the sky with the naked eye.

The camera was set for a 5 hour sequence of the Milky Way during this time and surprisingly it captured the sandstorm which was backlit by Grand Canary Island making it look like golden clouds.

Watch the Milky Way shining through a Sahara sandstorm.

Satellite Sun Outages

Twice a year, during the spring and fall, you may experience some degree of television interference due to a phenomenon known as "sun outages."

What is a sun outage?
A sun outage is an interruption in satellite signals caused by interference from solar radiation. The interference is caused when the sun is in direct line with a communication satellite and the sun's radiation overwhelms the satellite signal.

How long do they last?
Starting 2/29 and running through 3/8, interruption in TV service due to sun outages can last up to several minutes a day.

How do they affect watching TV?
During this time, you may experience interference with picture quality and sound when watching television. Sun outages do not affect internet or phone service.

Satellite Sun Outages | Optimum

'via Blog this'

The Christmas Planet

This month a planet, properly known as Kepler 22-b, was revealed by NASA.

They have discovered thousands of planets outside our solar system using the Kepler space telescope, but this one is the most Earth-like world discovered so far.

It is located in an area nicknamed by astronomers the Goldilocks Zone. That's because it's not too hot, not too cold, but just right for life.

And the planet has been nicknamed the Christmas Planet because three photos of a planet are needed from Kepler to be sure that 22-b was for real. A 22-b year is 290 days long and photo number three came during the 2010 holiday season, so...

The Christmas Planet is 600 light years away. It is about twice the size of Earth. The average surface temperature is 72 degrees Fahrenheit, which sounds pretty nice right now.

Farewell to the Phoenix

NASA's Phoenix Mars Lander has ended operations after repeated attempts to contact the spacecraft were unsuccessful. A new image transmitted by NASA's Mars Reconnaissance Orbiter shows signs of severe ice damage to the lander's solar panels.

The spacecraft succeeded in its investigations and exceeded its planned lifetime.

 

A view of one of the Mars Phoenix Lander's solar panels
from a composite of multiple exposures taken by the spacecraft's camera.
Image credit: NASA/JPL-Caltech/University Arizona/Texas A&M University Larger image

Phoenix reported on summer conditions at the far-northern Mars site where it landed May 25, 2008. The solar-powered lander completed its three-month mission and kept working until sunlight waned two months later.

Unfortunately, Phoenix was not designed to survive the dark, cold, icy winter.