Jan 30

What’s Up in the Sky

What’s Up in the Sky – February, 2018

A Super Blue Moon Eclipse

I’m going to cheat a little this month. Although the focus of this column is usually on astronomical events occurring in February, I will be describing an event that happens tomorrow. It’s always cloudy in February anyway.

I am talking about a total eclipse of the Moon. Lunar eclipses occur when the Moon passes through the Earth’s shadow. Unlike a solar eclipse where the Moon casts its shadow on the surface of the Earth, blocking the Sun from the view of only those in the shadow’s narrow path, a lunar eclipse is visible to anyone on the side of the Earth facing the Moon. Unfortunately, that won’t be us, at least not for long because the Moon will be setting over Lake Michigan just as totally begins at 8:00 a.m. And the chances for a clear horizon in late January around here are slim. But if it is clear and you have a view of the horizon, go for it.

But there’s more. I have written before how this column is sometimes inspired by locker room conversations after noon ball and this is no exception. The question was in regards to a “Super, Blue Moon”, a relatively rare event. The discussion morphed into questions about frequency and observability.

First some background. A “Super Moon” occurs when the Moon is at perigee (the point in its orbit closest to Earth) and is also opposite the Sun (a full Moon). The closeness will make it appear slightly larger although the effect is not noticeable to the naked eye. That is why there were no “Super Moons” twenty years ago – the term was invented by the Weather Channel to increase viewer interest. It has no astronomical significance.

The term “Blue Moon” originally referred to the third Full Moon in a season with four Full Moons (rather than the usual three). This is still known as a “seasonal” Blue Moon. But in a 1946 article in Sky & Telescope magazine a misunderstanding of this definition caused the author to erroneously describe the Blue Moon as the second Full Moon in a month. This definition was repeated on a program called “StarDate” in 1980 and even made it into Trivial Pursuit as an answer in 1986. Today, rather than a mistake, it is considered to be a second definition.

Both the seasonal and modern Blue Moons occur once every two or three years on average. That may seem puzzling considering that this year there is a Blue Moon tomorrow and then another one March 31. But that’s because February has too few days to ever have a second full Moon so a Blue Moon in January is always followed by another in March. The next one will be in October 2020.

Now add in the fact that tomorrow the Super Blue Moon will pass through the Earth’s shadow and we have the “Super Blue Moon Lunar Eclipse”. I don’t know how rare that is, but it is definitely very, very cool, just like most things up in the sky.

My thanks to Dr. David Myers, whose questions inspired this article.

This month in history:

Feb 6: Alan Shepard hits first golf balls on the Moon – 1971
Feb 15: Galileo Galilei born – 1564
Feb 18: Clyde Tombaugh discovers Pluto – 1930
Feb 19: Nicholas Copernicus is born – 1473
Feb 20: John Glenn is first American to orbit Earth – 1962
Feb 24: Detection of first pulsar (by Jocelyn Bell in 1967) is announced – 1968

Nov 28

What’s Up in the Sky

What’s Up in the Sky – December, 2017

2017 – An Historic Year for Astronomy

What must it be like to devote an entire career to the study of a particular field and in a period of about two months have two discoveries made for the first time in history? That’s what has happened to astronomers recently.

The events that have the astronomical community in orbit are the detection of two colliding neutron stars and the discovery of a fast-moving object from outside our solar system passing the Sun.

About 130 million years ago in a galaxy far, far away, two neutron stars – the strange, compacted cores of dead stars – crashed into each other. Known as a “kilonova” the explosion sent ripples through space-time and ejected heavy elements such as gold and platinum into space. That’s one new discovery right there – it was previously thought that these elements were formed in the supernova explosions of massive stars.

Several things make this observation so astounding. One is its rarity – astronomers estimate that such a collision occurs in a galaxy like our own perhaps a few dozen times per millions of years. Another is the fact that not only were the gravitational waves from the resulting explosion detected by LIGO, but also, two seconds later, scientists detected a flood of electromagnetic radiation from across the spectrum. This has allowed astronomers and astrophysicists to verify theories concerning some of the most fundamental questions in physics.

In addition verifying the source of heavy elements, they were able to show that gravity waves travel at the speed of light, determine the source of gamma ray bursts, and measure the expansion of the universe much more accurately. Not bad for a single observation.

The second historical event is notable more for its rarity rather than any revealing data it provides. But it is still pretty cool. I’m referring to the discovery of the first observed object known to have originated from beyond our solar system. That determination was made based on its speed and trajectory. It is currently speeding out of our solar system into interstellar space.

Actually, this is not the first interstellar object to make its way into our solar system. Spacecraft have collected and returned samples of interstellar dust and grains of it can be found in meteorites. But this was the first “macro object” of extra-solar origin to be observed.

Regarding the importance of this discovery, Paul Chodas with the Center for Near-Earth Objects Studies said, “we have been waiting for this day for decades”. It was another confirmation of the long-held theory that objects moving between the stars occasionally pass through our solar system.

All in all, it’s been a good year for what’s up in the sky.

This month in history:
Dec. 7: Galileo spacecraft enters Jupiter’s atmosphere – 1995
Dec. 8: Dragon 1, first private spacecraft to be recovered from orbit, is launched – 2010
Dec. 14: Gene Cernan, Apollo 17 astronaut, is last human to walk on Moon – 1972
Dec. 14: Tycho Brahe born – 1546
Dec. 20: Founding of Mt. Wilson Solar Observatory – 1904
Dec. 24: Apollo 8 astronauts give us inspirational moment from lunar orbit – 1968
Dec. 25: Isaac Newton born – 1642

Nov 01

What’s Up in the Sky

What’s Up in the Sky – November, 2017

Halloween and Astronomy?

Happy Halloween! This being the first time this column has been published on Halloween, I thought it might be fun to see if there was any connection between the holiday and astronomy. Turns out there is. And it stems from the customs and beliefs of early cultures.

Many Halloween traditions can trace their origins to the ancient Celtic festival of the harvest called Samhain (pronounced sah-win). But the date itself is also significant in an astronomical sense because it is a “cross-quarter date”.

We mark the beginnings of the seasons with what we call equinoxes and solstices, so the autumnal equinox marks the first day of autumn in September, and the winter solstice the first day of winter in December. But the dates roughly half-way between these seasonal boundaries, the cross-quarter dates, were also important to early cultures. (We still celebrate two other cross-quarter dates, Ground Hog day on February 2nd, and May Day on May 1st.)

To the early Celts, however, these dates marked the middle of the seasons, not the beginning, and so winter, the “dark season” actually began on the cross-quarter date approximately half-way between the fall equinox and winter solstice, October 31. This makes sense to me since November is much more winter-like than March and we often think of summer ending on Labor Day.

That’s where Samhain comes in. Roughly translated it means “summer’s end” and was the start of the dark season when everything died and the days grew cold. It was also the Celtic new-year’s eve and great bonfires were lit to keep evil spirits away. It was a time of both celebration and fear, as the light, living summer gave way to the dark, dead winter.

It was also a time of year when the well known star cluster, the Pleiades, reached its highest point in the sky around midnight. To the Celts, the Pleiades opened a path to the other world and when they reached their highest point in the sky, the barriers between the worlds broke down, and the souls of the dead could cross over into the world of the living.

The Full Moon is often associated with Halloween, usually depicted with the silhouette of a black cat or flying witch on her broomstick. Unfortunately, the Full Moon does not always fall on October 31, but it is a common image. This year, though, trick-or-treaters will be able to see an “almost-Full” Moon low in the southeast after dinner.

So I hope your day is somewhat enriched by the knowledge that your celebration has its origins up in the sky.

This month in history:
Nov. 3: The dog Laika is first living creature to orbit Earth, aboard Sputnik 2 – 1957
Nov. 9: Carl Sagan born. – 1934
Nov. 16: Interstellar message broadcast from Arecibo radio telescope – 1974
Nov. 20: Edwin Hubble born – 1889
Nov. 27: First photograph of a meteor shower – 1885
Nov. 30: Ten-pound meteorite strikes and bruises Alabama woman, Elizabeth Hodges-1954

Oct 21

What’s Up in the Sky

What’s Up in the Sky – October, 2017

An Historic Mission Comes to an End

On September 15, the Cassini spacecraft became part of Saturn when it melted into its atmosphere upon its final descent from orbit. NASA sent out a tweet that said, “Earth received Cassini’s final signal at 7:55 a.m., ET. Cassini is now part of the planet it studied.” The “Grand Finale” orbit that sent it plunging into oblivion was chosen as “moon protection”. Saturn has several moons on which conditions may be favorable for some life, and we didn’t want to contaminate it with any of our microbes.

Many readers know that the Cassini mission uncovered a number of mysteries through its extensive study of the planet’s rings, moons, atmosphere, magnetic field, and more. More than half a dozen previously unknown moons of Saturn were discovered by Cassini. It studied the planet’s seasons and spin. It also delivered a photo of Earth from Saturn that builds on the legacy of Carl Sagan’s pale blue dot.

The loss of Cassini marks the end of an era of “great missions” that used large, expensive, complex spacecraft such as Voyager and Galileo to accomplish their goals. Of course, these programs were tremendously successful and continued far past their designed time frames (Voyagers 1 and 2 are still sending back data!)

Cassini was launched in 1997 and reached Saturn in July, 2004, after flybys of Venus and Jupiter. It orbited the planet for the next 13 years, collecting data, taking magnificent photos and studying mysteries such as oceans of frozen methane on Titan, and salt water geysers on Enceladus, two of the planet’s moons.

Some of the scientists working on this project have been together since the planning and design stage, almost thirty years. For many, Cassini represents an entire career’s worth of work. The scientists became like family, watching each other’s kids grow up. They even formed a singing group.

For many of the 1000 people gathered at JPL (Jet Propulsion Lab) for the spacecraft’s final moments, the end of the mission was a bittersweet experience filled with mixed emotions. When asked about the moment contact with Cassini is lost, one scientist at mission control said, “Do we cheer or go into silence?”

But when you work on a project for 20 or 30 years with the same people, sharing important discoveries and contributing to an historic mission, it makes a lasting impression. One researcher described making discoveries with her colleagues as, “. . . a beautiful feeling; nothing like it in the world.”

Many of these project scientists will continue their work on other programs and some will retire. But the data collected during the entire mission will keep planetary scientists busy for a long time. The Cassini spacecraft has given us a great appreciation for the splendor of what’s up in the sky.

Aug 01

What’s Up in the Sky

What’s Up in the Sky – August, 2017

THIS IS IT!

In June I wrote about the wonders of witnessing a total solar eclipse like the one coming up on Monday, August 21, and encouraged readers to do some web searches for “information on locations and methods of safe viewing.”  Now, for those traveling to a viewing site along the path of totality, I will describe the eclipse’s “special events”, times during the event that you don’t want to miss.

I first must remind readers that at NO TIME should you ever look at the partially eclipsed Sun.  SOLAR ECLIPSE GLASSES should always be worn when observing the partial phases before and after totality.  Observing with a special solar telescope or one fitted with a proper solar filter is best done with an experienced observer who is familiar with the equipment.  Also be reminded that you have to be located along the path of totality, about an eight or nine hour drive south.

Now, about those “special” sights of interest.  The beginning of the eclipse occurs when the Moon first begins to cover the Sun.  For the next hour and a half the Moon moves slowly in front of the Sun, partially covering its disk.  View this phase best by projecting the image, do not look directly at the partially eclipsed Sun.

Since the timing of the events depends on your location, you will have to use outside resources such as solareclipsetimer.com to accurately predict them.  As the partial phase comes to an end, be aware of your total environment, the wind, the birds and insects, and the color of the sky both above and near the horizon.  As totality nears, be sure to watch through your solar eclipse glasses as the last sliver of the Sun disappears.  Immediately before this happens watch for “Bailey’s Beads” where the Sun still shines through the valleys on the Moon’s limb.  These gradually (in a few seconds) morph into a single, last bead that brightens dramatically and, when combined with the Sun’s corona (outer, bright atmosphere) forms the “diamond ring” effect.

Now totality begins.  In our area, it will last slightly less than three minutes.  It is not necessary to wear eye protection during totality, in fact you won’t see anything if you do.  The diamond will be gone but the beautiful ring remains.  You are standing in the shadow of the Moon and as it moves across the landscape you may be able to see its effects, depending on your view.  Some have witnessed “shadow bands” on the ground or the shadow itself moving over the distant horizon.

Check the time again and be ready to go back to eye protection for the end of totality when the Sun’s disk again is visible.  There may be a second diamond ring but afterwards the thin disk of the Sun will continue to grow.  During this last phase you will probably want to let it all sink in and form lasting memories.  In some circles it is customary to give a champagne toast to the most beautiful thing you will ever see up in the sky. (For a wonderful description of the eclipse, see: http://www.eclipse2017.org/2017/what_you_see.htm)

This month in history:

August 1:  Production of Saturn V rocket ends – 1968
August 3:  First in-flight space shuttle repair – 2005
August 6:  Curiosity rover lands on Mars – 2012
August 12: Echo 1 satellite launched – 1960
August 18: Helium discovered in the Sun – 1868
August 25: Voyager 2 flies past Neptune – 1989
August 28: Galileo spacecraft flies past asteroid Ida – 1993

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