May 04

What’s Up in the Sky

What’s Up in the Sky – May, 2019

Einstein’s Eclipse

One hundred years ago everything changed. Not all at once, not even as the years progressed, but by the end of the twentieth century what had begun on May 29, 1919 would dominate our technology. For it was on that day that a total solar eclipse captured the attention of the scientific community and introduced a new scientific theory to the public all over the world. It also propelled a little known scientist named Albert Einstein to international fame.

In 1915, as the First World War raged throughout Europe, Einstein published four revolutionary papers on general relatively, an extension of his earlier theory of special relativity, that showed that spacetime is connected to matter. He used his new theory to correct a flaw in Newton’s law of gravity that incorrectly calculated a certain aspect of the orbit of Mercury. General relatively predicted the orbit precisely.

But the scientific community was not convinced and another test was needed, this one to measure the amount of deflection of light by a massive object, the basis of “gravitational lensing” widely used today, and a method suggested by Einstein in 1911. All scientists needed was an opportunity to measure the precise positions of stars near the Sun’s disc. If the bending did exist then stars appearing close to the Sun would be in a slightly different position compared to where they normally are. This can only be accomplished during a total solar eclipse when the nearby stars become visible.

Several unsuccessful attempts were made following Einstein’s 1911 calculations of the bending, and it was fortunate for him that they were, for had they accurately measured the bending, it would have been different than his earlier predictions. But when, in 1915, he recalculated the deflection based on general relativity, the numbers turned out to be spot on. Had the earlier observations been successful, Einstein’s place in history might have been very different.

The war negated eclipse viewing opportunities in 1916 and 1918, but in March of 1919, just four months after the war’s end, Arthur Stanley Eddington, then director of the Cambridge Observatory, set out from Liverpool to Principe, an island off the West African coast. Meanwhile, a second group of distinguished astronomers traveled to northern Brazil for their observations and measurements.

Eddington’s journey to Principe was a grueling six and a half weeks by steamship, only made tolerable by an abundance of bananas, a delicacy to the rationing-weary Englishmen. The other team’s trip to Brazil with 14 crates of heavy equipment took two weeks, followed by a month’s delay before they could travel to their destination, about 50 miles inland.

On the day of the eclipse there was tension at both sites due to the threatening weather. The Brazil team was fortunate that the weather finally cleared and they were able to make accurate measurements. Eddington’s team was not as lucky but were still able to gather important data.

Upon returning to England and after several months of painstaking analysis, both teams determined that the amount of bending of the light was precisely what Einstein’s theory had predicted!

These experiments were daring, provided clear evidence, promised a scientific revolution, and gave people a much sought after positive story following four brutal years of war. Although no single experiment could prove relativity, the theory has been tested and confirmed countless times over the past century.

On July 2, 2019, another total solar eclipse will be visible from nearly the same locations, almost acting as a tribute to the centenary of the eclipse that revealed to us how the universe actually works.

For a more in depth description of this fascinating event, I recommend the article, A Relatively Important Eclipse, by Benjamin Skuse in the May, 2019, issue of Sky and Telescope magazine.

This month in history:
May 5: Alan Shepard becomes first American in space – 1961
May 9: Hyabusa, the first spacecraft to bring back a sample from an asteroid, is launched – 2003
May 11: Launch of first geostationary weather satellite – 1974
May 12: Adler Planetarium in Chicago opens, first planetarium in western hemisphere – 1930
May 14: Skylab is launched – 1973
May 25: President Kennedy gives speech challenging nation to land an astronaut on the Moon before the end of the decade – 1961
May 29: First experimental test of Einstein’s General Theory of Relativity successfully performed during total solar eclipse – 1919

Apr 01

What’s Up in the Sky

What’s Up in the Sky – April, 2019

Seeing Double

Many readers are familiar with double stars, the most well known probably being two stars in the handle of Ursa Major, the Big Dipper. Mizar, the bright star in the bend of the handle, and Alcor, its fainter companion, form a binary pair, known to the ancients and used as a test of warriors’ eyesight. But a closer look in even a modest telescope reveals that Mizar is itself a double star and was in fact the first double star to be discovered, in 1617. Recent observations with high-tech instruments reveal that all three members of this group are themselves double stars, making the system a true sextuple!

Now and in the coming months a number of double stars will come into view. Some can be observed with amateur equipment, so I would like to present a beginner’s guide to a few of them.

Let’s begin with Sirius, the brightest star in our sky and one of the easiest to find. Follow Orion’s belt toward the left until you come to it, shining like a beacon in the southwest. Its companion, known as Sirius B, was discovered in 1862 by Alvan Clark (using a pretty big telescope), and is a white dwarf star whose mass is roughly equal to that of the Sun, but is packed into a volume about the size of the Earth.

Above Sirius, in the constellation Gemini, is the star Castor, the right-hand member of the Castor and Pollux pair. Castor is an accessible binary for smaller telescopes. Its two components form a spectacular and bright blue-white pair, both of which are what is known as spectroscopic binaries. That means they can only be detected by analyzing their spectrum, the patterns of the light each emits. This is one way astronomers detect exoplanets which are much too dim to observe visually.

Returning to Orion we find another type of double star, a visual double. Look at the bottom star in the sword hanging down from the left side of his belt. A modest pair of binoculars shows it to be two stars, but these are not gravitationally bound to each other as all the previous examples are. One is actually several hundred light years farther away, but along nearly the same line of sight, making them appear to be close together.

I may be getting ahead of myself, but while we are on the subject of double stars, I must mention two of my favorites, the double-double in Lyra and Albireo in Cygnus. Although these two constellations dominate the summer sky, late night observers can spot them beginning in early April and on into May.

Around midnight at the end of the month, look northeast and you will see the star Vega, about thirty degrees above the horizon. It is the top right corner of an equilateral triangle of stars. Look closely at the star just to the left of Vega. Known as Epsilon Lyrae, it is a double star, easily visible in a pair of binoculars. If you are able to observe it through even a small telescope, you will see that each component is itself a double, hence the name double-double. It is truly a spectacular sight for small ‘scopes.

Alberio is the star at the head of Cygnus, the Swan, and consists of a yellow giant and a blue dwarf. The colors are distinct, even in binoculars, and are the reason some refer to Alberio as the U of M star.

I hope you will now be able to enjoy some double-star-gazing during your tours of what’s up in the sky.

This month in history:

April 2: First photograph of Sun taken – 1845
April 9: NASA selects original seven Mercury astronauts – 1959
April 12: Yuri Gagarin becomes first human in space – 1961
April 12: Columbia becomes first space shuttle to be launched – 1981
April 17: Apollo 13 returns to Earth – 1970
April 20: Apollo 16 lands on the Moon – 1972
April 24: China becomes the fifth nation to launch its own satellite – 1970
April 28: Eugene Shoemaker is born – 1928

Mar 04

What’s Up in the Sky

What’s Up in the Sky – March, 2019

We Should Bestow Awards on These Stars

In like a lion out like a lamb is usually a phrase that refers to the weather in March. But there’s also a connection to the constellation Leo, the lion, that will dominate the southern sky during the month of April. But as the winter constellations sink lower in the west, this is a good time to get one last look at them.

Facing the south an hour after sunset you can easily spot the prominent constellation Orion, the hunter. His two brightest stars represent his right shoulder (Betelgeuse) and left knee (Rigel). Betelgeuse is a red supergiant with a mass 10 to 15 times that of the Sun and is also almost 100,000 times more luminous. If it were located at the center of our solar system it would extend out between the orbits of Mars and Jupiter. Formed a mere 10 million years ago it is evolving rapidly and will most likely and its life in a supernova explosion some hundred thousand years from now.

Rigel is similar in age and mass but somewhat smaller with a diameter about the size of the orbit of Mercury. With a helium core it will continue to fuse heavier elements and eventually expand into a red giant before it suffers the same fate as Betelgeuse.

A close look at the sword extending downward from the left side of the belt reveals that the middle star is actually a nebula and the bottom star is a double. This can easily be seen with a pair of binoculars.

Follow the line of the belt down and to the left where you will see the brightest star in our sky, Sirius. Sirius is nearby at only 8.6 light years and is known as the Dog Star for its location in the constellation Canis Major, one of Orion’s two hunting dogs. Sirius has a white dwarf companion that orbits it every 50 years, but since it is 10,000 times fainter it cannot be seen with the naked eye. Above serious is Procyon, eighth brightest star in the sky, which is also orbited by a faint white dwarf.

Continue up to a pair of stars almost directly overhead. Castor and Pollux appear equally bright and are in the constellation Gemini, the Twins.

To the right of Gemini and directly above Orion is the constellation Auriga, the charioteer. Its brightest star. Capella, is very similar to our Sun, shining with a noticeably golden color. Complete the tour by continuing down to a V-shaped grouping of stars, the brightest of which is another red giant, Aldebaran. The group is actually a distant star cluster known as the Hyades. At 65 light years, Aldebaran is really much closer and represents the eye of Taurus, the bull.
Next month we’ll take a look at the constellation LEO, another gem up in the sky.

This month in history:
• March 1: Venera 3 impacts on Venus – 1966
• March 4: Jupiter’s ring is discovered – 1979
• March 14: Albert Einstein born – 1879; Gene Cernan born – 1934
• March 18: Voskhod 2 cosmonaut, Alexei Leonov, makes worlds first spacewalk – 1965
• March 22: Comet Hale-Bopp passes closest to Earth – 1997
• March 31: Saturn’s largest moon, Titan, discovered by Dutch astronomer Christiaan Huygens – 1655

Feb 12

What’s Up in the Sky

What’s Up in the Sky – February, 2019

Ultima Thule – A Blast From the Past

Late last year, an object with a very interesting name was in the news. That was Ultima Thule, the latest discovery made by the New Horizons spacecraft. Go to https://apod.nasa.gov/apod/astropix.html, click on “Archive” and look at the photo from January 29.

At that time not much was known about this object other than it had a weird name. In order to find out what we have discovered so far I turned to a reliable source, Dr. Harold Reitsema, a project scientist on NASA missions who worked on New Horizons. Dr. Reitsema is also a member of the Shoreline Amateur Astronomical Association, and Holland resident and agreed to an interview for this story.

“Thule” refers to the edge of the known world, and is a term that has been around for about a thousand years. “Ultima” simply reinforces that idea and is appropriate because it is the most distant object in the solar system to be visited by a spacecraft and that is where New Horizons is. It is an informal name chosen from a list of submissions to an internet poll. Currently, the real name is 2014 MU69 (which is kind of “nerdy” in Dr. Reitsema’s view) but even that is only temporary until the International Astronomical Union assigns a permanent name that follows current protocol.

Ultima Thule resides in the Kuiper belt, a region of the solar system that extends about 10 AUs beyond Pluto (an AU, or astronomical unit, is the average distance from the Earth to the Sun) and contains over a million asteroid-like objects ten kilometers or larger in diameter. It was discovered in 2014, eight years after New Horizons was launched. It took a massive effort by New Horizons team members using the Hubble Space Telescope, to pinpoint its location.

Based on these observations, New Horizons was able to make small corrections in its trajectory that allowed it to pass a little over three thousand kilometers (slightly less than two thousand miles) of its target. That’s like sinking a three pointer from over two hundred eighty miles.

So why Ultima Thule? What could we possibly learn from a tiny object so far away? Dr. Reitsema explained that the very early stages of the formation of the solar system are difficult to study due to a lack of data from samples dating back 4.5 billion years. Planets, their moons, and asteroids have all undergone changes since the solar system first formed. The craters on the Moon are an example. Even Pluto suffered a great collision that formed its moon, Charon. Dr. Reitsema explained that we wanted to “look at a very pristine thing that looks like it did when it formed”. So this object, undisturbed since its formation, is going to look like what “small things that got together and made bigger planets looked like originally”.

There is still more to learn about Ultima Thule and much evidence is forthcoming from pictures that have yet to be downloaded from the spacecraft. At the time of my interview, there was very little evidence of impact craters on its surface, but as you can see from the picture mentioned above, we continue to learn much each week as additional images arrive. That picture alone explains why people like Dr. Reitsema devote their careers to studying what’s up in the sky.

This month in history:
Feb. 1: Shuttle Columbia breaks apart during reentry killing all 7 astronauts – 2003
Feb. 7: First untethered spacewalk made by Bruce McCandless – 1984
Feb. 14: Voyager 1 looks back to take photo of solar system – 1990
Feb. 18: Pluto discovered – 1930
Feb. 20: John Glenn is first American to orbit Earth – 1962
Feb. 28: Charles Bassett and Elliot See, Gemini IX crew, die in plane crash – 1966

Dec 31

What’s Up in the Sky

What’s Up in the Sky – January, 2019

January Features the Moon and Planets

Whether you’re a late night person or an early bird, January has something for everyone.

You may recall last January 31st when there was a rare (the last one was in 1866) Super Blue Blood Moon, when the Moon is not only closest to Earth in its orbit (“Super”) and is the second full Moon of the month (“Blue”), but it is also totally eclipsed (“Blood”). Unfortunately, this rare event was not visible from West Michigan, but on January 20-21 this year, we will be in position to witness, weather permitting, a Super Blood Moon, just like last year, but without the “Blue” part.

The lunar eclipse begins around 10:30 p.m. with totality beginning about an hour later. The Moon will be deepest in Earth’s shadow at 12:12 a.m. During totality, see if you can spot the bright stars Castor, Pollux, and Procyon nearby. It’s also fun to imagine how the scene would appear to an astronaut on the Moon looking back at Earth. She or he would see the disc of Earth surrounded by a thin ring of red light from all the sunrises and sunsets happening on Earth at that moment. During totality, the Moon’s surface is lit only by this ring, thus the reddish hue of the Moon at that time. So mark your calendar for the night of January 20/21 to see this beautiful event.

Another celestial show will also occur this month, this one involving not only the Moon but also several bright planets. The only downside is that you will have to be out before sunrise to see it, but this time of year that’s during the morning commute.

You probably won’t be into looking at the predawn sky on New Year’s Day so rest assured that you won’t miss much if you wait until January 2nd. Looking southeastward around 7:30 a.m. you will see brilliant Venus just above a crescent Moon with slightly fainter Jupiter to the pair’s lower left. If by some miracle it is clear the following morning look for an even thinner crescent Moon just to the left of Jupiter.

Keep observing as often as possible to see the two bright planets move past each other as the month progresses with the minimum separation occurring on January 22. The show repeats at the end of the month and culminates with an even closer pairing, this time between the Moon and Jupiter on January 31.

With interesting sights all month, you can take advantage of any clear days to enjoy what’s up in the sky.

This month in history:
Jan. 1: Asteroid Ceres discovered by Giuseppe Piazzi-1801
Jan. 4: NASA cancels further production of Saturn V rockets-1970
Jan. 13: Galileo discovers Ganymede, moon of Jupiter-1610
Jan. 19: New Horizons spacecraft launched on it’s journey to Pluto-2006
Jan. 27: Apollo 1 astronauts Chaffee, White and Grissom die in fire in capsule-1967
Jan. 28: Seven astronauts killed when Space Shuttle Challenger explodes during launch-1986

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