Friday, August 7, 2020
Sunday, June 28, 2020
The solar cycle or solar magnetic activity cycle is a nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the solar surface. Sunspots have been observed since the early 17th century and the sunspot time series is the longest, continuously observed time series of any natural phenomenon. Accompanying the 11 year quasi-periodicity in sunspots, the large-scale dipolar magnetic field component of the Sun also flips every 11 years, however, the peak in the dipolar field lags the peak in the sunspot number, with the former occurring at the minimum between two cycles. Levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation, from active to quiet to active again, with a period of 11 years. This cycle has been observed for centuries by changes in the Sun's appearance and by terrestrial phenomena such as auroras.Wikipedia
Tuesday, March 31, 2020
￼Not very far in the night sky from the Andromeda Galaxy (our sister galaxy) you can find M33. It is about 2.9 million light years distant from our galaxy, but not often a target at public astronomy nights (i.e. SFU's Starry Nights). Under the best observing conditions - no light pollution and a really dark sky - this galaxy, the third largest in our local group, is visible to keen, dark adapted eyes without optical help. A pair of binoculars is a great help because M33 is a diffuse object - the amount of light it produces is distributed over an area about four times the apparent area of the Moon in the sky (see pages 317 and 333 in the Royal Astronomical Society's Observers' Handbook for the year 2020). You can understand that the sky conditions required for its visibility are unlikely to be met in a light polluted city night sky. Below is a photo I took via remote access to a Slooh.com telescope
Some on-line star applications call it the Pinwheel Galaxy. That is not generally accepted, because the name is normally given to M101, a galaxy in the constellation of the "Big Dipper", about 21 million light years away.
Saturday, February 1, 2020
It's been raining here for all of January, one day of no rain. February was not much better. From my astronomical point of view, it was the pits. I haven't taken part in one of SFU's Starry Night events since well before Christmas; Since October, most of the time the event had to be cancelled, mostly because of bad weather.
Another way to do some "armchair" astronomy is to take some pictures of the sky, preferably as seen from other latitudes. To this end I use one of the remote-controlled telescopes at Slooh.com, with locations on the Canary Islands and Chile. Here's a black-and-white image of the Tarantula Nebula.
"The Tarantula Nebula has an apparent magnitude of 8. Considering its distance of about 49 kiloparsec (160,000 light-years), this is an extremely luminous non-stellar object. Its luminosity is so great that if it were as close to Earth as the Orion Nebula, the Tarantula Nebula would cast visible shadows. In fact it is the most active starburst region known in the Local Group of galaxies. It is also one of the largest H II regions in the Local Group with an estimated diameter around 200 to 570 pc, and also because of its very large size, it is sometimes described as the largest although other H II regions such as NGC 604 which is in the Triangulum Galaxy could be larger. "
One parsec is the distance at which the radius of the Earth's orbit around the sun is seen at an angle of one arc second, that distance is 3.26 light years. That means that even from the nearest star (4 light years away) the Earths orbital radius has an angle of less than one arc second.
Let the weather gods do their thing - if you have a roof over your head, and a safe place to live, you can evade them anyway.
Thursday, November 28, 2019
This article begins with a part of my life which is germane to this story. I was born in Berlin about three months before the start of World War II. My father was conscripted into the war effort; military duty was mandatory. As a result, I saw very little of him and I have only sporadic memories of the occasions when he was on furlough. I remember the end of the war more clearly - being subject to the evacuations and bombings tend to sharpens one's mind. My father was taken prisoner of war in Russia at that time and I did not see him for about two years. When he came home in 1947, he was a very sick man and went straight into the hospital. I visited him many times during his stay there. On one of these visits he showed me a book he was reading. It was the German translation of a book about the Moon and the craters on it. The English title is: The Moon, Considered as a Planet, a World, and a Satellite. The authors are James Nasmyth and James Carpenter. The book was published in 1876.
At that time, the origin of lunar craters was still a subject of contention: either by volcanic activity or by meteor impacts (this question was finally resolved in the 1960's and, except for a few volcanic features, impact is the answer). My father showed me a picture of a lunar crater in that book; the picture actually showed a plaster of Paris model, made by the authors to show the lunar craters' volcanic nature. That picture has been in my memory ever since, as well as the title of the book, and its authors. The picture (see below) was the start of my interest in Astronomy; I don't know why it made such an impression on me. The book is actually my last memory of my father - he died a couple of months later. Nowadays, antibiotics would have saved his life, but they were non-existent at that time, especially not in war-torn Berlin.
I subscribe to the Sky and Telescope magazine. The December 2019 issue includes an article by Klaus Brasch, professor at California State University in San Bernadino. The article is entitled "Just Over a Century Ago"; in it, the book about the Moon I described above is mentioned, including the picture of the lunar crater that caught my original attention in 1947. I looked up Nasmyth and Carpenter on the internet, and immediately found a link to lynx-open-ed.org, which showed a dissertation on the two authors and their firm conviction of the volcanic origin of lunar craters, in the German version of their book. The book's title page and the lunar crater picture are shown below. Published in 1876, the original information in the translated text was already about 70 years old by the time I saw it.
Still an active member of the Vancouver centre of the RASC, involved in public astronomy days, using my telescopes, I never get tired of what the sky has to offer. Our current technologies have made astronomy into a science with connections to most other sciences, witness astrophysics, astrobiology, astrochemistry, quantum physics, computer science, geography and geoscience, space travel, etc. These connections often lead to interesting conversations with some of the people attending our star parties.
Friday, August 30, 2019
A couple of weeks ago, I took a picture through the remote Slooh.com telescope of a comet coming in from the outer reaches of the solar system, an area called the Oort cloud. This is a theoretical cloud, thought to extend from about 2,000 AU (Astronomical unit - the distance Earth to Sun - about 150,000,000 km) to 200,000 AU. It supposedly contains icy planetesimals (Wikipedia contains some detailed information).
Because its outer reaches are so far from the Sun, the planetesimals can be affected by the gravitational influences of other objects in our galaxy, and occasionally my be deflected towards our Sun. There is a reasonable chance that this comet is one such object. Here's the picture:
The name of the comet is Comet C 2018 W2 Africano. It's the fuzzy spot to the right of the dashed line. At the time of writing, the comet is moving at 50 km/sec towards the Sun and will be at Perihelion (closest to the Sun) on Sep.5 and closest to Earth on Sep 27. It may become visible in common telescopes and possibly even binoculars. Africano is currently in the constellation Camelopardalis. Look for more current positions in TheSkylive.com as time progresses
Thursday, June 20, 2019
Right now, the planet Jupiter is visible in the sky fairly low in the south in the evening. That's a comfortable and convenient time to observe it.
Jupiter is the most massive, and the largest planet in the solar system. All the other planets would easily fit into it's volume, with room to spare for a second set of solar system planets. We have not detected a solid surface on Jupiter yet; it is one of the two gas giant planets orbiting the sun (which one is the other?). It has the mass of over 300 Earths and around 1200 times the volume. with a diameter about 11 times that of Earth. It is a gas ball with a diameter of 143,000 km and consists of Hydrogen (about 90% and 9+% Helium, with traces of Methane and other elements). That's somewhat reminiscent of the Sun's composition; some people are calling Jupiter a "failed star". However, in order to start the necessary nuclear fusion, Jupiter would have to have about ten times more mass. None-the-less, internal pressures are huge, enough to transmute Hydrogen and Helium into a liquid metallic state. At the centre, there may be an ice/rock core.
At opposition (i.e. now, August/September 2019) it is close to Earth, since Sun, Earth, and Jupiter are positioned almost in a straight line. That means that Jupiter is somewhat more than 4 Astronomical Units away from us (1 AU = 150 million km). Therefore, the light coming to us from Jupiter takes around 35 minutes to get here. Add to that the distance of Jupiter to the sun, and you get about 45 more minutes. Since all solar planets shine by reflected sunlight, we see Jupiter illuminated by sunlight which left the sun around 80 minutes (1 hour and 20 minutes) earlier.
Even though Jupiter is 5 times as far from the sun as Earth, and receives only 1/25th (square of distance law) of Earth's sunlight, it is, after the Sun, the Moon, Venus, and the space station in orbit around Earth, the brightest object in the sky. That is due to its large diameter and relatively high reflectivity (albedo). It appears large enough from Earth to show some details in even a small telescope, as well as the Galilean moons. Even binoculars will show the dance of the moons around Jupiter. Larger telescopes, i.e. 4", 5", 8" and larger will show many always changing details on Jupiter, including the great red spot, a local storm as large as our Earth, undergoing quite drastic changes at this time. Jupiter turns once in just under 10 hours; constantly showing new features on its surface. The prominent cloud bands (mostly methane, some ammonia, water ice, traces of hydrogen sulfide) move at hundreds of kilometers/hr., they are far more energetic than the worst storms on Earth.
The Galilean moons orbiting Jupiter show relatively fast changes in relative positions. These are easily followed even in binoculars. The moons themselves are very different from each other. In order of increasing distance from Jupiter they are Io, Europa, Ganymede, and Callisto. Io is the most volcanically active of any planets or moons in the solar system, Europa has a very smooth, icy surface, possibly about 50km thick, with a vast layer of liquid water suspected underneath; Ganymede is the largest moon in our solar system, and has a quite complex composition; Callisto is the third largest of the moons around any of the solar system planets, after Ganymede, and Saturn's moon Titan. It has a heavily cratered surface. Only the largest of Jupiter's moons' features are visible through earth-based telescopes, and a large telescope is needed even for that purpose.
Look up The RASC's Observer's Handbook; Wikipedia and other astronomical on-line sources to contain more details for Jupiter-related phenomena.
People have spent a lifetime exploring Jupiter's system, and now the latest orbiting probes have sent back very detailed data.
Jupiter is truly the King of the Solar System planets.
Wednesday, April 10, 2019
M 35 is estimated to be about 2800 light years away, while NGC 2158 is about 5 times farther away. These two clusters are not related, their proximity is just a matter of perspective from our location in our galaxy. NGC 2158 can be observed through telescopes, while 10x50 binoculars resolve the brighter stars in M 35. This cluster is roughly 110 Million years old, pretty young, if we consider the age of the Universe (about 13.7 billion years). M 35 has a diameter of about 23 light years. We're getting closer to it at a speed of about 5 km/sec.
There are a number of "easy targets" in the sky at this time of year; I picked just one.
Friday, March 29, 2019
Many times, during our public astronomy nights, people have asked about buying a telescope. If this request comes from someone who has just looked through a telescope for the first time, I recommended to start with binoculars. This is the second step after having acquired at least a little familiarity with "naked eye" constellation, location of some of the major "targets", and the their seasonal visibility. I also explain the reason for the timing on the orbital position of the Earth in its orbit around the sun.
Having used telescopes for most of my life, I always use binoculars as helpers to locate objects I want to look at. I am talking here about finding them "manually", not using computerized telescopes. In many cases, people already own some binoculars, they've just never thought of using them to look at the sky. Most of these "found" binoculars are quite suitable for this kind of use.
For astronomical purposes, binoculars with larger front lenses are better. Astronomical objects, other than the Moon and the bright planets, tend to be quite faint; the larger the front lens, the more light you gather, that makes these faint targets easier to see. Personally, I use two pairs of binoculars with the magnifying power (power equals magnification) of 10 and one stabilized pair with the power of 15 (see fig. 1, left to right).
Thursday, January 24, 2019
This time, we got a lucky break. The weather cleared up just a few hours before the recent total lunar eclipse. Our granddaughters, who are also members of the RASC (as I am), took some nice pictures of the eclipse (I set up a telescope on the rear porch at home and just observed by eye, binoculars, and the telescope). I downloaded only one image from Slooh. com the remotely-accessed organization.
We will have no more total lunar eclipses this year. A partial lunar eclipse this year will occur on July 16. The next total lunar eclipse will occur on May 26, 2021. On November 19, 1921 will be a partial lunar eclipse. Another total lunar eclipse occurs on May 16, 2022. In between occur several penumbral lunar eclipses, on Jan 10, 2020, June 05, 2020, July 05, 2020, Nov 30, 2020 all usually almost invisible, because the brightness of the full moon varies very little. Penumbral lunar eclipses are caused by the Moon just missing the Earth's shadow.
The Moon's orbital plane differs from the Earth's orbital plane around the Sun by about 5 degrees. There are two crossover points, the ascending and descending nodes. Both solar and lunar eclipses (partial and total) can occur only when these nodes are "in line" with the Sun, and the Moon is very near, or at one of them. That also means the both types of eclipses occur at either "new Moon" (solar) or "full" Moon (lunar). These nodes slowly move around the plane of the Earth's orbit, giving rise to various series of "eclipse cycles" which repeat over hundreds of years.
You can let your imagination play by thinking about what these various types of eclipses would look like if you found yourself on the Moon...
Tuesday, November 6, 2018
By Derek on February 17, 2011 6:40 PM
That's a real galaxy, though, called NGC 2841, about 45 million light years away from our own. And neither it nor its Star Wars companion would look anything like that if we were seeing them with our own eyes.
Consider the fact that we're right inside a galaxy, and for most of us living in cities, the Milky Way, which is the view through the thickness of our closest spiral arm, is entirely washed out by light pollution. I don't think my daughters have ever seen it, in fact. You need a pretty dark sky, preferably on a moonless night, to see it properly.
Wednesday, October 3, 2018
At our public star parties a number of people have never seen the impressive objects we usually show through a telescope ask about how, and at what cost they could acquire a telescope to look at the stars, planets, the Moon, and other objects in the sky.
My long-time come-back to this question for people who are new to looking at the sky through one of our members' or SFU's Trottier observatory's telescopes are questions of my own. I ask whether they own a pair of binoculars. If the answer is yes, then the my next question is: have you ever looked at stars through them? Many people have never even thought of doing this. To those people who have done it, I put this question: would you know where to look for the Andromeda galaxy (or some other object in the sky)? The answer many times is "no".
With the apps available on computers, tablets, smartphones, etc., many people compare the sky portrayed on these devices with the sky visible at the time. That's a legitimate approach, but, in my opinion, if one comes to rely on these devices, one usually does not "learn" the sky.
I grew up at a time when these devices were "science fiction". Having had an interest in astronomy since I was eight years old, knowing the sky is an "innate" feeling for me, at least as far as the northern hemisphere is concerned. I've not much time closer to the equator, therefore I don't have the same familiarity with the southern sky.
In my younger years I did some serious astronomy, for instance submitting observations to the AAVSO (American Association of Variable Star Observers) regarding variable stars, Zürich sunspot numbers, occultation timing, and other things. These activities, and many others are now done by both amateur and professional astronomers (the two categories really overlap nowadays, since the technologies available are now highly sophisticated and not very expensive), and generate very precise and detailed results.
At this time in my life, my greatest enjoyment comes from our public star parties. I get a kick out of comments like "wow", "cool", "amazing" when people are looking through one of my telescopes at the sky. In particular, I feel very happy when a young person comes up with these comments.
Adults who are "newly exposed" are equally amazed. The objects which usually are the source of this are the "jewels" of the sky: Venus and its phases, Jupiter and its moons, Saturn's rings, our Moon's craters, open and globular star clusters, etc.
Here are the recommendations I usually make:
(1) When outdoors, preferably under a dark sky, use only your eyes to get to know the sky and constellations using one of the star finders we hand out freely on various occasions, or find a printed or on-line star atlas. Familiarize yourself with the constellations and their annual positions at various times of the year. Dig deeper, and become knowledgeable about the Earth's orbit and how that relates to these times of visibility. Try to find objects which our unaided eyes can readily perceive (Pleiades, Hyades, Milky Way, compact constellations, etc.). If you feel that you'd like to see these targets in more detail, then
(2) use your binoculars to find these objects. If you are a young person, 7x50 binoculars are ideal. Your age and personal preferences have an effect on what may be your perfect binoculars. Almost all binoculars will show far more detail in the night sky than the "naked" human eye. Using binoculars will "train" you to find sky objects. At first you may spend some time to succeed, but you quite quickly become better at it.
Many very descriptive dissertations have been written about the use of binoculars in astronomy. Even advanced astronomers, at least those who are involved in the visual observing, have their favorite binoculars on hand when observing. Personally, when I'm setting up one of my telescopes, I always have binoculars with me. They are very helpful in locating objects for which I want to use the telescope. Once you have become familiar with their use and characteristics, and if you are looking for even more detail, a telescope may be your next "step up".
(3) Before you buy a telescope, understand the basic requirements. Beside the size of your contemplated purchase, understand differences between the various types. This is a much-discussed and written-about subject. The best way to find out is to attend star parties, such as the ones run by the RASC, or SFU's Trottier Observatory, because you will usually meet people who are using different types of telescopes. You will also become aware of the fact that purchasing a telescope entails having to buy a sturdy, and accurately manufactured telescope mount. The best telescope is next to useless unless it can be held steady, and does not shake with every little breeze. The matching of telescope to its support is another important topic.
Computerized telescopes are a helpful addition to the range of telescopes available. Again, unless you have learned how to find objects in the sky as described in (1), (2), and (3), you likely won't get to know the sky in the detail necessary. Getting to know the sky "in depth" is best done by learning to point a telescope "manually".
If you become a member of the RASC, you'll have access to many benefits. As a member, you can borrow one of the RASC's library books, and/or a loaner telescope for a limited time. You also receive several publications, chief of which is the RASC's annually published Observers' Handbook. It contains a wealth of data, among which you'll find detailed information about binoculars, telescopes, human eyes, and upcoming monthly events (eclipses, occultations, planetary positions - a plethora of facts and discoveries). The Handbook is used by professional and amateur astronomers world-wide. The RASC also owns the magazine "Skynews", and publishes the RASC Bulletin and local RASC centre newsletters. All these are included in the membership.
Try it - I think you'll like it.
Monday, August 13, 2018
Aldergrove Lake Park for viewing the Perseids every year. It is a big event for the Parks Board and the public, and matches the Royal Astronomical Society of Canada's mandate to promote an interest in astronomy and associated sciences to the public.
I wrote this last year in my post about viewing the Perseid meteor shower (August 13, 2017, in italics):
Aldergrove Park near Abbotsford is used for public viewing when the Perseid meteor shower peaks annually on August 12. The park administration sets up a tent for us (the RASC), and reserves some space nearby to set up telescopes. Some of our members, and sometimes invited speakers, give several talks regarding astronomical events (past, present, and future). It's a rain-or-shine occasion. If it rains, telescopes are not set up outside, but may serve as exhibits inside the tent.
The Aldergrove Park administration promotes this event. This is the only time in the year at which overnight camping is allowed in the park. Many people usually attend.
This year, an unfortunate fire on a barge carrying old, recycled cars, docked in the Fraser river on the day before this event created a lot of smoke. This affected much of the Lower Mainland, both on the day before, when we were involved with the "Starry Night" event at Simon Fraser University's Trottier Observatory, and at Aldergrove Park. "Perseid" day itself was cloudy, with local rain showers. Toward evening, the smoke had cleared, and some large, blue stretches appeared in the southwestern sky and drifted east to where Jupiter, Saturn, and Mars would be located at dusk. I made my way to Aldergrove Park, found our assigned area (same as last year), decided that chances were reasonable for viewing, and set up my telescope.
Our RASC Vancouver centre librarian William happened to spot Venus with his binoculars well before sunset, so he and I trained our telescopes on that brightest of our planetary siblings. I got a couple of minutes view of it, a couple of members and the public had a chance to view it as well, and then a cloud covered Venus. That was the last view I had of it for the evening.
Our activities ended just before midnight; had it been clear, we would have stayed all night for the public to have a look at interesting astronomical objects - the Perseid meteors especially, of course. Well, we hope that next year's Perseid meteor date will have a clear night sky. This is the same sentiment I expressed last year.
As I write this, the smoky sky has returned. The cause appears to be some fairly large forest fires on Vancouver Island. So the night from August 12 to 13 (which was when the actual maximum of Perseids was expected) turned out to be a bummer, too.
Maybe "deja vu" of smoky skies is turning out to be the new normal.