Mars Slides Behind Moon This Month

In mid-February, a waning crescent Moon glides among Mars, Jupiter, and Saturn in the predawn sky. For many viewers in North America, the Moon actually covers Mars on February 18th.
Sky & Telescope

It’s fitting that with my intense focus on Malacandra throughout January that upon finishing the Mythgard Academy class this week I have a major astronomical event featuring Mars to look forward to in less than two weeks.

I can take good advantage of this occultation since I live in the middle of the country just shy of 40 degrees north latitude. If I were visiting my daughter in the Pacific Northwest, I’d have a bit more dark time but might not see it as well being at a more northern latitude at 47 degrees.

Image via IOTA. See the loop at the upper right above North America? As the moon rises in the predawn hours on February 18, 2020, in this part of the world, Mars will covered over by the moon. But, later on before dawn, you can watch Mars reappear from behind the moon’s dark side. Read more.

Actually, not just Mars will be in the spotlight in mid-February. Three planets are center stage in the predawn skies starting February 18th (see first graphic above). Listen to Sky Tour courtesy Sky & Telescope for some viewing tips and other astronomical tidbits for February observing.

Sky Tour Podcast for February 2020

My only concern will be the weather, which in February in Kansas, is dodgy at best.

Keeping my fingers crossed and as always keep looking up!

Welcome to Winter Solstice Eve Morning

Good morning and welcome to the last half day before Winter. Officially, Winter begins tonight after ten o’clock (Central time)

Winter Solstice 2019 Countdown

Enjoy the shortest day of the year because I’m looking forward to the longest, darkest night of the year – every amateur astronomers dream.


Today, my son, daughter-in-law and grandson are driving here from Texas. They left before dawn and we anticipate their arrival late this afternoon.

With the help of my daughter, who arrived earlier this week, my main floor living area is mostly baby proof. And the new furniture was delivered Thursday afternoon. And Friday, Rachelle setup the Christmas tree and last night over home-made pizza we decorated (or rather she decorated because she’s the artistic one).

Rachelle and I will spend part of the day shopping, taking advantage of her Costco membership to stock up on food she can eat (corn allergy) and for the rest of the family as well. While I have a Christmas goose in the freezer, I need to plan for other meals and sides. Instead of just Terry and I to feed, I’ll have three to four times that many to provide for.

So we are ready for family gathering and making new memories until we once again scatter back to our nests for the new year.

There’s a Star in the East

Long winter nights.

Crisp clear skies.

Denser colder atmosphere.

These are a few of my favorite things during the winter months and they add up to darker skies and brighter stars.  This weekend also has a few things going for it, astronomically, and also happens to be Twelfth Night (tomorrow, January 5th) and Epiphany (the day after) commemorating the journey of the Three Wise Men guided by a Star in the East.


Observing Highlights for this Weekend (courtesy of “The Sky This Week” at Astronomy.com):

Friday, January 4
Although people in the Northern Hemisphere experienced the shortest day of the year two weeks ago (at the winter solstice December 21), the Sun has continued to rise slightly later with each passing day. That trend stops this morning for those at 40° north latitude†. Tomorrow’s sunrise will arrive at the same time as today’s, but the Sun will come up two seconds earlier Sunday morning. This turnover point depends on latitude. If you live farther north, the switch occurred a few days ago; closer to the equator, the change won’t happen until later in January.

† I’m just 68 miles south of the Kansas-Nebraska border, which juxtaposes with the 40th parallel.  Weird fact discovered this morning via Google Maps:  The Kansas Highway that is literally a block west of my house (K-7) ends at the border and turns into 666 Avenue (see map screenshot below).
Continue reading “There’s a Star in the East”

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?”

Continue reading “Do You Hear What I Hear?”

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

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.

Continue reading “Just A Sun-Day Drive Around the Galactic Neighborhood”

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

Continue reading “Stellar Death Blasts”

Flashy, Bizarre, Weird Degeneracy

Just in time for Halloween, my topic this week focuses on electron degeneracy pressure specifically to delve into how “A degenerate gas does not expand when the temperature increases as an ordinary gas does.”

In 1923, Arthur Stanley Eddington derived a formula to relate the luminosity of a star to its mass, and in the same year correctly interpreted high-density, white dwarf stars as being formed of matter so dense that atomic electrons have collapsed from their orbits, a substance we now call degenerate matter. (Levy, p. 116)

Young giant stars of a certain size, between .4 and 2 solar masses, have helium rich cores squeezed by gravitational force into a crystal-like solid.  At these pressures, the atoms become completely ionized, separately into nuclei and electrons and are so closely crowded together that become influenced by the Pauli exclusion principle phenomenon.  Two identical particles are not allowed to exist in the same place and time.  As the electrons are pressed closer and closer together, the exclusion principle forces many of them to move faster and faster so they do not become ‘identical’ (meaning occupying the same space and moving with the same speed of adjacent electrons) and consequently this motion increases the repulsion between the electrons.  This state provides pressure in the core preventing it from collapsing and is referred to by astronomers as degeneracy.  Thus, low-mass giants with helium-rich cores are supported by electron degeneracy pressure. (Comins, p. 335)

Very high density matter, the structure of which is modified by the intense gravity. Particles, which must “squeeze”, create the degeneracy pressure.

If that wasn’t bizarre enough, here’s where it gets weirder:  A degenerate core’s pressure does not change with temperature.  Continue reading “Flashy, Bizarre, Weird Degeneracy”

Absolute Magnitude Luminates Absolutely

This week I want to discuss “What might cause the closer of two identical stars to appear dimmer than the farther one?”

Apparent Magnitude: A measurement of the brightness of stars without regard to their distance from Earth.

  • The scale in use today starts with the star Vega and an apparent magnitude of 0.0
  • Objects brighter than Vega are assigned negative numbers.  For example. Sirius, the night’s brightest star, has an apparent magnitude of -1.44
  • The scale was extended to include the dimmest stars visible through binoculars and telescopes.  For example, a pair of binoculars can see stars with an apparent magnitude of +10

Ignoring distance for a moment, all other things being equal, the closer of two identical stars will appear brighter (have a smaller apparent magnitude) to us than the more distant star.  When we account for the difference in distance, we use either or two measurements:  absolute magnitude and luminosity.

Absolute Magnitude: The brightness a star would have at a distance of ten parsecs (10 pc) or 32.6 ly. Continue reading “Absolute Magnitude Luminates Absolutely”

Solar Cycle Stranger Things

I’ve reached the halfway point through my Introduction to Astronomy class. This week marks the eighth week of fifteen, sixteen if you count the first week where we just spent time getting to know each other and exploring the textbook and getting the lab software, Starry Night, installed and licensed. Last week, we reached the outer limits in the Kuiper Belt and Oort Cloud of our solar system where only comets and Voyagers I and II have ventured. Now we’ve snapped back to study our closest star, Sol, or more commonly just the Sun. My topic for discussion responds to the following question:

Why is the solar cycle said to have a period of 22 years, even though the sunspot cycle is only 11 years long?

Some surface features on our active Sun vary periodically in an eleven year cycle.  The Sun’s magnetic fields which cause the surface changes vary over a twenty-two year cycle.  The relatively cool and slightly darker regions, commonly called sunspots, are produced by local concentrations of the Sun’s magnetic field piercing the photosphere.  The latitude and number of sunspots on average vary during the same eleven year cycle.  But the hemisphere where the Sun’s north magnetic pole anchors during one eleven year cycle will have south magnetic poles during the next.  Because it takes a full twenty-two years for the magnetic poles to return to their original orientation astronomers refer to the entire solar cycle.   The magnetic dynamo model posits that many transient features of the solar cycle are caused by the effect of differential rotation and convection on the Sun’s magnetic field.  The Sun’s differential rotation (different speeds at different latitudes) causes its magnetic field to become increasingly stretched like a rubber band.  The bands can’t break so they periodically untangle themselves with the help of trapped gases which leak out (sunspot) and gradually settle back under the photosphere, when the sunspot disappears.  The most recent reversal of the Sun’s magnetic field occurred in 2013.  We are currently at the tale end of Solar Cycle 24.  (Comins, 2015, p.  272-83)

Continue reading “Solar Cycle Stranger Things”