Do You Hear What I Hear?

My final astronomy discussion topic attempts to answer “Why are some wavelengths of radio emission better than others in searching for extraterrestrial civilizations?”

Plot of Earth's atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation.

Plot of Earth’s atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation.

 

Radio waves can travel immense distances without being significantly altered by interstellar medium.  They penetrate dust and gas and are the logical choice for interstellar communication.  Astronomers have been listening for signs of extraterrestrial life using the radio spectrum since the 1950s and 60s – long before scientists had discovered the means of detecting exoplanets.  But the sheer number of both radio frequencies and directions to search proved daunting and raised question like “Which frequencies should be used to maximize the odds of detecting an alien signal?”

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Merry Bowlingmas

Welcome to my annual roasting of my building’s attempts at modern art holiday decorating.  When I showed my husband this year’s photo, his first words were: “Bowling pins?”

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unHoliday Lobby Decorations (2017)

I had to concede his point.  At least this year the dominant color is red with a swash of green.

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Universal Song Remains the Same and Beyond All the Light We Cannot See

For such a small chapter, this week’s topic on Cosmology has some large and deep concepts.  I’m attempting to delve into “How did the period of inflation cause the universe to become homogeneous and isotropic?

Definitions

Big Bang ~ Universe began as an extraordinarily hot, dense primordial atom of energy and caused expansion, just like an explosion.  Before that moment, nothing existed, not even space and time.  Rather, the explosion created spacetime, which continues to expand.  (Comins, 446)

Inflationary Epoch ~ During this epoch, the universe became so large that today we can only see a tiny portion of it and that is limited by the speed of light.  The growth and size of the observable universe occurred in a very brief time.  (Comins, 451)

Cosmic microwave background (CMB) ~ If the universe began with a hot Big Bang, then calculations indicated the energy remnants should still fill all of space today. The entire universe’s temperature should be only a few kelvins above absolute zero.  This radiation’s blackbody spectrum peak should lie in the microwave section of the radio spectrum.  (Comins, 446)

Isotropy of CMB ~ The cosmic microwave background radiation is almost perfectly isotropic – the intensity is nearly the same in every observable direction.  Isotropy isn’t just limited to observed blackbody radiation, but is also found on a large scale when exploring the number of galaxies found in different directions.  (Comins, 448)

Homogeneity ~ The uniformity with distance (the numbers of galaxies stays roughly constant with respect to both distance and direction) of the universe is homogeneous. (Comins, 449)

Fine-Tuning Big Bang

Any viable theory of cosmology, including the Big Bang, must explain the isotropy and homogeneity of the universe.  Numerous refinements have been posited and as a result the theory now provides an accurate scenario for the evolution of universe from a tiny fraction of a second after it formed and onward to today.  (Comins, 449) Continue reading

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Just A Sun-Day Drive Around the Galactic Neighborhood

This week I’m tackling the subject of our Sun’s motion through the Milky Way Galaxy and approximately how long one orbit is.

The Milky Way Galaxy has two major spiral arms, named the Perseus Arm and the Scutum-Centaurus Arm.  There are also smaller less pronounced arms, including the Sagittarius Arm, the Norma Arm, The Local Arm (aka the Orion Spur) and the Outer Arm.  Our solar system resides in the Orion Spur (Local Arm), branching off from the larger Perseus Arm.  During the summer months in the northern hemisphere, we predominantly observe the Sagittarius Arm, including the galactic center, which appears as steam from the Tea Pot asterism in the constellation Sagittarius.  (Gaherty, 2016)  Over the winter, we’re looking away from the galactic center and through the Perseus Arm.  (Comins, 396)

Artist’s concept of what astronomers now believe is the overall structure of the spiral arms in our Milky Way galaxy. The sun resides within a minor spiral arm of the galaxy, called the Orion Arm. Image via NASA and Wikimedia Commons.

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To Not Blame Those Sent for Being Sent

via We Veterans Thank You

Two score and four years ago, my uncle returned from the Vietnam War to being ‘cursed, ridiculed’ and possibly assaulted because we blamed the soldiers for our government’s execution of foreign policy.  And I do mean ‘our’ government, since, for better or worse, our government is of, by and for the people.  We did this.  There is no one else we can blame.

In the intervening decades until his retirement in 1998, he returned from other wars to a very different homecoming.  For that, I’m eternally grateful.  By the time he returned from both Gulf Wars, I was no longer in the second grade where I was oblivious and sheltered from world events, but during a time when I had children of my own in grade school whom I wanted safe and sound.

For his service and sacrifice, he has my gratitude.  As do all his contemporary veterans.

War is an unpleasant business. Some wars are necessary; some are not. Regardless, it is terrible to send our sons and daughters to kill or be killed. But, until we learn not to practice war anymore, I’m happy that America has learned not to blame those sent for being sent.

— Col. Ronald Andrea, USAF, Retired

 

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To Serve Quietly (or Not) Against the Dying of the Light

This morning I woke early, as I nearly always do, but with a melancholic mood fogging my mind.  Two Hallmark movies and a cup of hot tea later and I still could not shake the malaise.  I turned off the television and grabbed the closest half-finished book handy and continued my perusal of Cosmic Discoveries with David Levy.  The subtitle for chapter nineteen was a quote I’ve heard many times but which I had never read the original source.  Since the chapter also started with another quote from the same work with a byline to the poet, I decide there’s no time like the present to read the original poem.

My tablet was charging across the room so I grabbed my smartphone and searched on the phrase and poet and got a crazy amount of hits – no surprise.  I read the Wikipedia article first to get some background on the poet and the when and partial why he wrote his now famous and often quoted poem.  Next, I returned to my results (from Wikipedia) and selected the first hit that contained the complete short poem.

I read it three times, because I read somewhere or was told by someone you should always read a poem three times.  I didn’t make it through the third stanza of the first reading before I couldn’t see my screen for the tears.  Damn poets! And at one point in my life I actually aspired to be a poet.  But life pretty much crushed the creativity out of me so I just enjoy those who had more courage than I to pursue their creative spark.

Good men, the last wave by, crying how bright
Their frail deeds might have danced in a green bay,
Rage, rage against the dying of the light.

— Dylan Thomas, ‘Do Not Go Gentle Into That Good Night

Reading this poem today reminded me of the sometimes quiet, always courageous sacrifices willingly given to us by our military service men and women.  Their continuing fight against the dying of the light allows me, my family, my friends, my acquaintances, my coworkers – all of us living in this great country that is the home of the brave and the land of the free – because of them.

Thank you, veterans, for your service.

Thank you for not going gently into any night and raging against the dying of the light to keep us safe and free.

Thank you.

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Stellar Death Blasts

This week I discuss types of supernovae, specifically relating to the scenario where “Hydrogen lines are prominent in Type II supernovae but absent in Type Ia.  Type Ia supernovae decline gradually for more than a year, whereas  Type II supernovae alternate between periods of steep and gradual declines in brightness. Type II light curves therefore have a step-like appearance.  Explain!”

Supernovae are classified as Type I or Type II depending upon the shape of their light curves and the nature of their spectra.

The question I really wanted to ask is ‘What happened to Type I or Ib?’ and the answer to that question was easily found in this chart:

Supernovae Taxonomy

Supernovae Taxonomy

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