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SkiesIdaho
Skies
February 2008
Vol.5 No.2
Idaho Skies is a column for beginning amateur astronomers and those interested in astronomy. Suggestions about the column are gladly accepted by the columnist, at paul.verhage@boiseschools.org
This month, look for the star, Procyon. Procyon, the lucida of the constellation of Canis Minor (the Little Dog) is the seventh brightest star in the sky. During February, Procyon appears in the southeast and to the upper left of the brightest star in the sky, Sirius.
If you were born in 1997, then Procyon is your birthday star this year because the light of Procyon you see tonight left the star 11 years ago. The name Procyon comes from the Greek word meaning Before the Dog and refers to the fact that in mid latitudes, Procyon rises shortly before Sirius, the Dog Star.
Procyon has twice the diameter of our sun due to its 70% greater mass. It’s greater temperature and diameter combine to make Procyon over seven times more luminous than the Sun. Procyon has consumed enough of its hydrogen that it can now fuse helium. In several tens of millions of years, just a blip of time for our sun, Procyon will expand into a red giant star.
White dwarf companion stars orbit both Procyon and Sirius. White dwarfs are old stars that have consumed their supply of nuclear fuel. Without fusion to support them, the force of gravity has compressed them into spheres the size of planets, or about 100 times smaller that they use to be. A cubic centimeter of white dwarf weighs about a ton. Imagine your car fitting on a teaspoon. Physicists call matter this dense, degenerate. It’s only the repulsion between electrons that keeps degenerate matter from collapsing further. Over billions of years, white dwarfs cool from white, to yellow, then to orange, red, and finally to black. Probably, there is no white dwarf in the universe old enough to have cooled into a black dwarf.
We begin the month with a near conjunction between Jupiter and Venus. On the 1st, both brilliant planets are visible after 6:30 AM in the east. Their distance apart will be half of a degree, or the angular distance across the moon. Venus is to the upper left and slightly dimmer Jupiter to the lower right. You should be able to see this pair until the sun rises, and even later, if you know were to look.
While you’re out, look for Antares, the lucida of Scorpius to the crescent moon’s left. This scene is best viewed through your binoculars.
Though a little difficult to see, the thin crescent moon appears to the left of Venus and Jupiter on the morning of the 3rd. You should begin looking low in the east for them by around 6:30 AM because by 7:00, the sky may be too bright to see the moon. A pair of binoculars will help you see them, though.
Three days later (late evening of the 6th) the moon reaches new. If we lived in Antarctica, we’d be able to see a solar eclipse today.
February 8 – 14
Novelist Jules Verne was born 180 years ago on the 8th. Considered one of the fathers of the science fiction genre, Verne is probably the third most translated author in the world. Verne’s science fiction stories are in many ways, prescience of future events. He accurately described submarines in his story, 20,000 Leagues under the Sea and many of the elements in From the Earth to the Moon match those in the Apollo 11 mission to the moon. Verne died in 1905 at age 77.
The moon reaches perigee on the 13th. The moon’s closest distance from the center of the earth this month is only 230,043 miles. At a jogging speed of six miles per hour, it would only take you four years and five months to jog to the moon.
A couple of hours later, the moon reaches the first quarter phase. The moon appears as a half moon tonight, the best shape to go moon watching. Look for details along the moon’s terminator, or boundary between day and night. Along here, shadows appear their longest and really bring out the details on craters ands mountains.
In honor of the works of the French science fiction writer, Jules Verne, the European Space Agency (ESA) has named its first automated transfer vehicle (ATV) after him. The launch of ATV-1 (Jules Verne) is scheduled (as of early December 2007) to take place on the 14th. Its destination is the International Space Station, or ISS. ATV-1 launches on top of Europe’s largest rocket booster, the Ariane 5. Jules Verne carries four solar arrays for power and inside it will be tons of supplies for the ISS.
On Valentine’s Night, the moon appears near the star clusters, Pleiades and Hyades. So take your Valentine out to see these clusters and the half moon tonight. Be sure to bring binoculars for your best views.
NASA launched the first geosynchronous satellite 45 years ago on Valentine’s Day, February 14, 1963. The satellite was the American communication satellite, Syncom 1. Once successfully placed into Earth orbit its kick motor fired to send it to a geostationary orbit. However, after 19 seconds of firing, Syncom-1 stopped transmitting. Probably, the kick motor exploded, destroying the satellite. Later in 1963 NASA successfully launched Syncom-2 into the proper orbit where it provide radio and television communications between ground stations on earth. Syncom-2 was a squat cylinder, two feet in diameter and one foot tall. Solar cells wrapped about its cylindrical body and provided the satellite with 28 watts of power. The most famous of the three Syncom satellites, Syncom-3 relayed live coverage of the 1964 Tokyo Olympics to the United States.
It was the work of Hermann Noordung and Arthur C. Clarke that brought the possibility of geostationary satellite communication to our attention. Satellites located 22,300 miles above the equator take exactly 24 hours to orbit the Earth. From our perspective on the ground, the satellite hangs fixed in the sky. That apparent motionlessness makes it much easier to keep antennas trained on the satellite. Not only is it easier to track a satellite in geostationary orbit, but since it’s motionless, it’s always there providing communications.
Are you looking for Mars? Then you’re in luck; the Moon guides you there on the night of the 15th. Mars appears as the light orange star to the Moon’s left. Their distance apart is three degrees, or six lunar diameters. In three dimensional space however, their distance apart is really 84 million miles.
You’ll be able to find the Beehive star cluster easily on the night of the 18th. Look below the moon less than half a binocular’s field of view for a large sprinkle of stars. More stars are visible if you move the moon outside the view of your binoculars. In dark skies, this cluster is visible to the unaided eye as a faint, fuzzy star.
The 19th is the 535th anniversary of Nicolas Copernicus' birth. Best known for the modern heliocentric theory, Copernicus (1473 to 1543) was a well educated Catholic cleric. He was not really an astronomer; in fact, astronomy played a tiny part in his life. Yet, he developed a model of the solar system based on observation and mathematics that placed the sun at its center. Since the sun was at the center of the solar system in his model, it’s called a heliocentric model. Copernicus was not the first person to propose a heliocentric model of the solar system. The ancient Greeks and Arabs had done the same centuries prior. However, Copernicus was the first to develop a scientific model. Started in 1514, Copernicus’ greatest work was not published in final form until he was near death. Legend has it that Copernicus saw the first copy of his book, On the Revolutions of the Celestial Spheres, on the day he died (May 24, 1543). Initially there was no backlash against his theory; it was well-supported by the evidence and known to many religious figures of the time. It was only after the trial of Galileo that the Catholic Church banned Copernicus’ book.
Yippee! We get to see a total lunar eclipse on the night of the 20th. Other then it may be cold that night; this is a great astronomical event. The eclipse begins at 5:36 PM for Idaho (4:36 for Oregon and 6:36 for the Midwest), but won’t be visible in Idaho until 6:13 when the moon rises (it’s visible even later in Oregon). The lighter outermost shadow of the earth is called the penumbra and the darker innermost shadow is called the umbra. Typically, it takes an hour before we can faintly see the penumbra on the moon. So don’t expect the eclipse to be obvious as soon as it begins. Mid eclipse occurs at 8:26 for Idaho (7:26 for Oregon and 9:26 for the Midwest) and the moon could appear bright copper red, dark charcoal, or any color and shade in between. The last vestiges of the eclipse will disappear around 10:15 PM for Idaho. Don’t miss this eclipse, as it’s our only one for 2008.
During the lunar eclipse, you’ll see the star Regulus above the moon and Saturn to the moon’s left.
Beginning the night of the 23rd, the Zodiacal Light is well placed for viewing until about March 8th. During the next three months, the Zodiacal Light rises steeply above the western horizon after sunset. It appears as a faint pillar of light that is best seen with the unaided eye. It’s faint enough that you need a dark location and a moon between last and first quarter to see it.
Saturn reaches opposition on the night of the 24th. What does this mean? It means the ringed world rises near sunset and sets near sunrise. At opposition, the planet is at it’s nearest to Earth for 2008. Saturn appears as a cream-yellow star to the unaided eye and binoculars. It doesn’t twinkle like the other stars unless the air is very turbulent. You’ll need a small telescope with a minimum magnification of 25 power if you want to see its rings. Therefore, you don’t need to purchase an expensive telescope to see Saturn, its rings, and some of its satellites well.
Forty years ago on the 24th (February 24, 1968) astronomer Jocelyn Bell and her college advisor Dr. Anthony Hewish found a one inch long squiggle on a chart recording from their radio telescope. That short squiggle was so perfectly regular in time, that at first, they wondered if they had discovered the radio beacon of an extraterrestrial civilization. Instead, they had discovered the regular radio pulses of a rapidly rotating neutron star, or pulsar.
Physicists, like Russian L. Landau, had predicted the existence of the ultra-dense remains of dead massive stars since 1932. At the end of their lives, massive stars are unable to support their weight through nuclear fusion. In a spasm, they rapidly collapse, emitting a blast of neutrino radiation and explosively fusing much of the remaining light elements in their outer layers. Protons and electrons near the center of the star are crushed into neutrons and then crushed again with the neutrons already in the star’s core. What remains is a gigantic atomic nucleus, roughly the size of a city but containing the mass of a star. A teaspoon of a neutron star has the same weight as a mountain on earth.
Shrinking a star down in size by a factor of 80,000 increases its spin rate by the same factor. Therefore, while pulsars originate as stars with a rotation period similar to our sun, or 30 days, when crushed to just 20 miles across, they spin faster than 100 times per second. Creating a neutron star doesn’t just increase it rotation rate, it also increases the strength of its magnetic field. The combination of a rapid rotation rate and strong magnetic field creates a machine capable of launching powerful beams of radiation from its north and south poles. When the pole of a rotating neutron star sweeps past the earth, we detect its beam of radiation as a blip in a radio telescope.
Here’s another difficult event to look for this month. Shortly before morning of the 27th, Mercury is one degree above Venus. You’ll definitely want binoculars to see this. At 7:00 AM, Venus is the bright star six degrees, or about one binocular field of view, above the east-southeast horizon. Right above it is fainter Mercury.
The moon is at apogee on the 27th. The moon’s greatest distance from the center of the earth this month is 251,309 miles. That puts the moon 21,266 miles farther way than it was at perigee on the 13th.
The moon is at last quarter on the morning of the 28th. Therefore, you won’t see the moon unless you go out after midnight or look for it in the morning as you drive to work.
This Month’s Topic
Nucleosynthesis is the creation of atoms heavier than hydrogen. The only place this occurs to any significant amount today is inside the core of stars and during supernovae explosions. Physicist Arthur Eddington proposed that stars shine through nuclear fusion (the combining of two lighter atoms into a heavier atom) in 1920. However, it wasn’t until the publication of Burbidge, Burbidge, Fowler and Hoyle in 1957 that the process was fully understood for the first time.
For stars like our sun, it’s during a process called the proton-proton chain that the nuclei of four hydrogen atoms combine to form a single nuclei of a helium atom. It begins when two hydrogen nuclei (two protons) collide to form a deuterium nucleus. The deuterium nucleus contains a proton and neutron, so one of the protons must first change itself into a neutron. This is only possible after a proton absorbs enough energy from its environment to emit a positron (anti-matter version of the electron) and some energy. The process is slow though; a proton waits, on average, for one billion years before absorbing the right amount of energy to become a neutron.
The newly minted deuterium nucleus (called a deuteron) then collides with another proton to become a light isotope of helium. This event releases a gamma ray, which the sun will eventually convert to heat and visible light.
At the sun’s core temperature, the next most likely step is the fusion of two light isotopes of helium. This results in a normal isotope of helium and two free protons. There are other fusion reactions occurring in the sun, but none are as probable as the fusion of two light helium isotopes.
If we compare the mass (think weight) of four hydrogen atoms to the weight of a helium atom, we find the helium weighs less than it should. In fact, a helium atom weighs 0.7% less than the sum of four hydrogen atoms. This is really odd when you realize that neutrons weigh more than protons. So a single helium atom should weight as much as four hydrogen atoms plus a little extra for its two neutrons. That mass is missing because it was converted into energy during the fusion process. The amount of energy created is described by Einstein’s famous equation, E= MC2. It says that the amount of energy in a mass equals the mass times the speed of light times itself again. Light travels at a tremendous speed, so squaring the speed of light yields an even larger number. It’s this conversion of mass into energy that powers the stars.
In young stars that are heavier than the sun, there’s a different fusion process occurring. This fusion process is a cyclical process involving carbon, nitrogen, and oxygen and called the CNO process. In the CNO process, a carbon nucleus collides with a hydrogen nucleus (proton) to become an unstable isotope of nitrogen. The nitrogen isotope eventually decays back into carbon, but now it’s a heavy isotope of carbon. The carbon nucleus then fuses with a second proton to become a stable nitrogen nucleus. The nitrogen nucleus then later fuses with a third proton to become an unstable oxygen nucleus. The unstable oxygen isotope decays to a heavy nitrogen nucleus, which then collides with a fourth proton. The resulting nucleus is unstable and breaks into a carbon and helium nucleus. In the CNO process, four hydrogen nuclei have fused together to form a helium nuclei with the help of a carbon atom. At the end, a carbon nucleus returns to help the next four hydrogen nuclei fuse into helium.
To create heavier elements, like metals, neutrons are slowly absorbed by the nuclei in a stellar core. This process, called the slow process, or s-process, creates heavier isotopes every time a nucleus absorbs a neutron. However, neutron rich atoms are unstable. To become stable again, one of the neutrons undergoes beta decay to convert into a proton. With the lose of a neutron and the gain of a proton, the nucleus becomes a new and heavier element. The neutrons that power the s-process come from the decay of unstable carbon and neon nuclei inside the star.
In very heavy stars, their internal pressure creates temperature as great as 200 million degrees. In stars this hot, two helium nuclei, or alpha particles, can collide to create atoms of beryllium. However, this beryllium is very unstable. So within 0.00000000000000026 seconds, it decays back into two alpha particles (helium nuclei). To create elements heavier than beryllium, a third alpha particle must collide with the very unstable beryllium before it has a chance to decay. Since the second collision must occur almost simultaneous with the first collision, astrophysicists call the process the triple alpha process. Once a stable carbon nucleus has formed from three helium nuclei, further collisions with alpha particles create nuclei of oxygen, neon, magnesium, silicon, sulfur, and argon.
The process stops at iron. There is no fusion process that can generate energy from iron. So how do even heavier elements, like uranium form? That occurs in a supernovae explosion and is the topic for another month.
The Royal Society of Canada, Observer’s Handbook 2008
Baalke, Ron, February 2008 Space Calendar, 28 Nov 2007, <www.jpl.nasa.gov/calendar/>
Kaler, James, Stars, <www.astro.uiuc.edu/~kaler/sow/>
Night Sky Explorer (software)
Wikipedia, Jules Verne, 26 Nov 2007, 27 Nov 2007, <http://en.wikipedia.org/wiki/Jules_Verne>
European Space Agency, International Space Station ATV-01, 27 Nov 2007, <http://www.esa.int/SPECIALS/ATV/index.html>
Wikipedia, Nicolaus Copernicus, 28 Nov 2007, 28 Nov 2007, <http://en.wikipedia.org/wiki/Nicolaus_Copernicus>
NASA, Goddard Spaceflight Center, 28 Nov 2007, <http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/bell.html>
Burnham, Robert Jr. Burnham’s Celestial Handbook, Dover Publications, 1978
Wikipedia, Procyon, 28 December 2007, 2 January 2008, <http://en.wikipedia.org/wiki/Procyon>
Wikipedia, Nucleosynthesis, 20 December 2007, 2 January 2008, <http://en.wikipedia.org/wiki/Nucleosynthesis>
Science in School, Fusion in the Universe: Where your jewellery (sic) comes from.., 6 June 2006, 8 January 2008, <http://www.scienceinschool.org/2007/issue5/fusion>
The Astrophysics Spectator, Fusion of Helium, 21 September 2005, 8 January 2008, <http://www.astrophysicsspectator.com/topics/stars/FusionHelium.html>
Dark Skies and Bright Stars,
Your Interstellar Guide