Currently, Polaris (Alpha α UMi) shines at magnitude 2.0 and lies just 0.7° from the North Celestial Pole (NCP). Precession of the Earth’s rotation axis will bring the NCP to within 0.5° of Polaris in March 2100, its minimum distance.
The situation for the South Celestial Pole (SCP) is not such a happy circumstance. The nearest naked-eye star to the SCP at present is neither near nor bright. Sigma Octantis at magnitude 5.5 is not easy to see with the unaided eye, and being 1.1 degrees away from the SCP doesn’t win it any awards. Besides, precession is moving the SCP farther away from Sigma Oct, not nearer.
One wonders, will precession someday bring us a south celestial pole star worthy of the name? Even, perhaps, comparable to Polaris? Here’s what our stargazing descendants can look forward to:
So, around 8100 A.D. Iota Carinae and around 9220 A.D. Delta Velorum will serve admirably as southern pole stars every bit as good as Polaris does now in the northern hemisphere.
Now, for the northern hemisphere…
Up until the year 10,000 A.D., no northern pole star will be as good as Polaris is now, though 4.8-magnitude 9 Cephei will be very close to the north celestial pole around 7400 A.D.
Thought you might enjoy seeing what deep sky objects will come close to the celestial poles, so those are listed in the above tables as well.
I am so very proud of what hundreds of thousands of Americans of all ages did today, marching in hundreds of anti-gun-violence rallies all across our nation. I’m especially proud of the students. We had a huge group of marchers in Mineral Point, Wisconsin (students included), and I was glad I participated.
I do not want to live in a country where everyone is armed to the teeth. You know, you have to decide what kind of a world you want to live in and then work towards that goal, no matter how difficult.
I was devastated and angry when John Lennon was shot to death in New York in 1980 outside his apartment building by a very disturbed man (it is almost always a man, isn’t it?). I mean, who the hell would kill a musician? I will never get over it. On that day (and many times since), I decided “enough is enough”. Gun ownership should be a privilege that has to be earned, not a right. And weapons of war do not belong in the hands of private citizens—ever. If that involves repealing the Second Amendment to the United States Constitution, then so be it. But “we the people” never get a chance to vote on gun issues, do we?
If gun owners in this country can’t support much stricter and sensible gun laws, then maybe we should peacefully go our separate ways. Gun lovers can have their country (a dystopia, really), and the rest of us can live somewhere else. I would support a civil separation, but never a civil war. (Besides, we know what side has most of the guns.)
“The young do not know enough to be prudent, and therefore they attempt the impossible, and achieve it, generation after generation.”
We continue our series of excerpts (and discussion) from the outstanding survey paper by George F. R. Ellis, Issues in the Philosophy of Cosmology.
The physical explanatory power of inflation in terms of structure formation, supported by the observational data on the fluctuation spectra, is spectacular. For most physicists, this trumps the lack of identification and experimental verification of the underlying physics. Inflation provides a causal model that brings a wider range of phenomena into what can be explained by cosmology, rather than just assuming the initial data had a specific restricted form. Explaining flatness (Ω0 ≅ 1 as predicted by inflation) and homogeneity reinforces the case, even though these are philosophical rather than physical problems (they do not contradict any physical law; things could just have been that way). However claims on the basis of this model as to what happens very far outside the visual horizon (as in the chaotic inflationary theory) results from prioritizing theory over the possibility of observational and experimental testing. It will never be possible to prove these claims are correct.
Inflation is one compelling approach to explaining the structure we see in the universe today. It is not necessarily the only one, but it currently has the most support. Basically, a tiny fraction of a second after the Big Bang, the universe expanded dramatically. Around 10-36 seconds after the Big Bang the universe had a diameter on the order of 1.2 × 10-27 meters. To put that size in perspective, the diameter of a proton is between 0.84-0.87 × 10−15 meters. So, when inflation began, the entire universe had a diameter almost a trillion times smaller than a single proton! 10-34 seconds later when the inflationary period was coming to an end, the size of the universe was a little over half the distance to Alpha Centauri!
The basic underlying cosmological questions are:
(1) Why do the laws of physics have the form they do? Issues arise such as what makes particular laws work? For example, what guarantees the behaviour of a proton, the pull of gravity? What makes one set of physical laws ‘fly’ rather than another? If for example one bases a theory of cosmology on string theory, then who or what decided that quantum gravity would have a nature well described by string theory? If one considers all possibilities, considering string theory alone amounts to a considerable restriction.
(2) Why do boundary conditions have the form they do? The key point here is, how are specific contingent choices made between the various possibilities, for example whether there was an origin to the universe or not.
(3) Why do any laws of physics at all exist? This relates to unsolved issues concerning the nature of the laws of physics: are they descriptive or prescriptive? Is the nature of matter really mathematically based in some sense, or does it just happen that its behaviour can be described in a mathematical way?
(4) Why does anything exist? This profound existential question is a mystery whatever approach we take.
The answer to such questions may be beyond the limits of experimental science, or even beyond the limits of our intellect. Maybe, even, these questions are as meaningless as “What lies north of the north pole?1” because of our limited intellect. Many would claim that because there appears to be limits to what science or human intellect can presently explain, that this constitutes evidence for the existence of God. It does not. Let’s just leave it as we don’t know.
Finally, the adventurous also include in these questions the more profound forms of the contentious Anthropic question:
(5) Why does the universe allow the existence of intelligent life?
This is of somewhat different character than the others and largely rests on them but is important enough to generate considerable debate in its own right.
Well, a seemingly flippant answer to this question is we wouldn’t be here if it didn’t, but that begs the question. Perhaps intelligent life is the mechanism by which the universe becomes self-aware, or is this just wishful thinking? In the end, I am willing to admit that there may be some higher power in the universe—in the scientific pantheist and humanist sense—but I will stop short of calling that “God” in any usual sense of the term.
The status of all these questions is philosophical rather than scientific, for they cannot be resolved purely scientifically. How many of them—if any—should we consider in our construction of and assessments of cosmological theories?
Perhaps the limitations of science (and, therefore, cosmology) is more a manifestation of the limitations of our human intellect than any constraint on the universe itself.
One option is to decide to treat cosmology in a strictly scientific way, excluding all the above questions, because they cannot be solved scientifically. One ends up with a solid technical subject that by definition excludes such philosophical issues. This is a consistent and logically viable option. This logically unassailable position however has little explanatory power; thus most tend to reject it.
Let’s call this physical cosmology.
The second option is to decide that these questions are of such interest and importance that one will tackle some or all of them, even if that leads one outside the strictly scientific arena. If we try to explain the origin of the universe itself, these philosophical choices become dominant precisely because the experimental and observational limits on the theory are weak; this can be seen by viewing the variety of such proposals that are at present on the market.
And let’s call this metaphysical cosmology.
1Attributed to Stephen Hawking
Ellis, G. F. R. 2006, Issues in the Philosophy of Cosmology, Philosophy of Physics (Handbook of the Philosophy of Science), Ed. J. Butterfield and J. Earman (Elsevier, 2006), 1183-1285.
Ryden, Barbara. 2003. Introduction to Cosmology. San Francisco: Addison Wesley.
We are all going to miss Stephen Hawking. His incredible intellect, and his even more remarkable determination to make something of himself despite a terrible affliction, has been a universal inspiration all over the world. Stephen Hawking was the individual equivalent of the Apollo lunar program. He raised the bar when almost everyone else we see nowadays is lowering it. He succeeded against all the odds.
Now would be a good time to watch (or rewatch) five extraordinary documentaries and films about Stephen Hawking and his ideas.
Edmund Weiss (1837-1917) and many astronomers since have called asteroids “vermin of the sky”, but since October 4, 1957 another “species” of sky vermin made their debut: artificial satellites. In the process of video recording stars for possible asteroid occultations, I frequently see satellites passing through my ~¼° field of view.
I’ve put together a video montage of satellites I’ve recorded between June 21, 2017 and October 20, 2017. The component events are presented chronologically as follows:
10-20-2017 (2 satellites)
You’ll notice that sometimes the satellite crosses the field as a moving “dash”. That’s because sometimes I used longer exposure times to record a fainter target star.
In general, the slower the satellite is moving across the field, the higher is its orbit around the Earth. One must also consider how much of the satellite’s orbital motion is along your line of sight to the satellite. In the following video clip, you’ll see a slow-moving “tumbler” satellite moving from right to left across the top of the field.
179462 (2002 AJ202)
On January 10th of this year, I figured out how to identify satellites crossing the telescope field of view using the amazing program Guide 9.1, which I use for all my observatory research work. On March 4th, I was hoping to be the first to record the asteroid 3706 Sinnott passing in front of a star. This asteroid is named after Sky & Telescope Senior Editor Roger Sinnott, whom I had the good fortune to work with in writing the article “A Roll-Down-Roof Observatory” in the May 1993 issue of Sky & Telescope, p. 90. Roger is amazing. He took an article that I had written and edited it in a way that only lightly touched my original text yet ended up saying what I wanted to say even better than I was able to say it myself. The mark of a great editor! Anyway, I’m sure Roger remembers me and I was looking forward to giving him the news that I had observed the first stellar occultation by “his” asteroid. Alas, it was not to be, because, as so often happens, the too-faint-to-be-seen asteroid passed either above or below the target star. The consolation prize, however, was recording a third stage Long March Chinese rocket booster (CZ-3B R/B; NORAD 43004U; International # 17069D) passing through the field. This rocket launched on November 5, 2017, and added two satellites to China’s Beidou positioning network. As you can see in the light curve below, the rotation period of the rocket booster is a bit longer than the 19 seconds of usable video I had.
Once in a great while, I record a telescopic meteor. Here are two.
Hughes, D. W. & Marsden, B. G. 2007, J. Astron. Hist. Heritage, 10, 21
Fermilab is a name well known to all physicists. When I was an astrophysics undergraduate student at Iowa State University in Ames, Iowa in the mid-to-late 1970s, I remember that several members of our large high energy physics group made frequent trips to Fermilab, including Bill Kernan and Alex Firestone. At the time, it was the best place in the world to do high energy physics. What is high energy physics? Basically, it is the creation and study of new and normally unseen elementary particles formed by colliding subatomic particles into one another at very high velocities (kinetic energies).
On Sunday, March 4, a group of us from the Iowa County Astronomers met up at Fermilab for an afternoon tour of this amazing facility. We were all grateful that John Heasley had organized the tour, and that Lynda Schweikert photo-documented our visit.
Our afternoon began with an engaging talk by Jim Annis, Senior Scientist with the Experimental Astrophysics Group: “Kilonova-2017: The birth of multi-messenger astronomy using gravitational waves, x-rays, optical, infrared and radio waves to see and hear neutron stars”. Here he is showing a computer simulation of an orbiting pair of neutron stars coalescing, an event first observed by the LIGO and Virgo gravitational wave detectors on 17 August 2017 (GW170817), and subsequently studied across the entire electromagnetic spectrum.
One of the amazing factinos I remember from his talk: even though neutrinos were not directly detected from the GW170817 event, the matter in colliding neutron stars is so dense that neutrinos push material outwards in what is called a neutrino wind. Yes, these are the same neutrinos that could pass through a light year of solid lead and only have a 50% chance of being absorbed or deflected, and pass through your body at the rate of 100 trillion every second with nary a notice.
Even though CERN has now eclipsed Fermilab as the world’s highest-energy particle physics laboratory, Fermilab is making a new name for itself as the world’s premier facility for producing and studying neutrinos. This is a fitting tribute to Enrico Fermi (1901-1954)—after whom Fermilab is named—as Fermi coined (or at least popularized) the term “neutrino” for these elusive particles in July 1932.
Basic research is so important to the advancement of human knowledge, and funding it generally requires public/government funding because practical benefits are often years or decades away; therefore such work is seldom taken up by businesses interested in short term profit. However, as our tour guide informed us, the equipment and technology that has to be developed to do the basic research often leads to practical applications in other fields on a much shorter time frame.
Thoughts Inspired by Leon Lederman: A Footnote
I had the great privilege in October 2004 of attending a talk given by Leon Lederman (1922-), winner of the 1988 Nobel Prize in Physics and director emeritus of Fermilab. I listened intently and took a lot of notes, but what I remember best besides his charm and engaging speaking style was his idea for restructuring high school science education. The growing scientific illiteracy in American society, and the growth of dogmatic religious doctrine, is alarming. Lederman advocates that all U.S. high school students should be required to take a conceptual physics & astronomy course in 9th grade, chemistry in 10th grade, and biology in 11th grade. Then, in 12th grade, students with a strong interest in science would take one or more advanced science courses.
Teaching conceptual physics (and astronomy) first would better develop scientific thinking skills and lay a better groundwork for chemistry, which in turn would lay a better groundwork for biology. Whether or not a student chooses a career in science, our future prosperity as a society depends, in large part, on citizens being well-informed about science & technology matters that affect all of our lives. We also need to be well-equipped to assimilate new information as it comes along.
It is in this context that I was delighted to read Leon Lederman’s commentary, “Science education and the future of humankind” as the last article in the first biweekly issue of Science News (April 21, 2008). He writes:
Can we modify our educational system so that all high school graduates emerge with a science way of thinking? Let me try to be more specific. Consider Galileo’s great discovery (immortalized as Newton’s First Law): “An isolated body will continue its state of motion forever.” What could be more counterintuitive? The creative act was to realize that our experience is irrelevant because in our normal experience, objects are never isolated—balls stop rolling, horses must pull carts to continue the motion. However, Galileo’s deeper intuition suspected simplicity in the law governing moving bodies, and his insightful surmise was that if one could isolate the body, it would indeed continue moving forever. Galileo and his followers for the past 400 years have demonstrated how scientists must construct new intuitions in order to know how the world works.
I’d like to take Lederman’s comments one step further. Whether it be science, politics, economics, philosophy, or religion, we must realize that most ignorance is learned. We all have blind spots you could drive a truck through. Our perceptions masquerade as truth but sometimes upon closer inspection prove to be faulty. Therefore, we must learn to question everything, accepting only those tenets that survive careful, ongoing scrutiny. We must learn to reject, unlearn if you will, old intuitions and beliefs that are harmful to others or that have outlived their usefulness in the world. We must develop new intuitions, even though at first they might seem counterintuitive, that are well supported by facts and that emphasize the greater good. We must, all of us, construct new intuitions in order to make our world a better place—for everyone.