Friday, August 7, 2020

At last, a naked-eye comet


After a fairly lengthy time of "comet starvation" we finally had an appearance of a comet which, while not super-bright, was visible to the naked eye. Comet Hale-Bopp in 1997 was the last one to be so visible. Using binoculars brought out a pretty impressive view of this "new" comet  (NEOWISE C/2020 F3), even in the light-polluted sky in our part of the city. Without the coved-19 pandemic in progress, the RASC would have held many public astronomy meetings; now this can only be approximated virtually (i.e. Zoom, and similar applications).

NEOWISE C/2020 F3 was discovered on March 27, 2020 by NASA's "Wide-field Infrared Survey Explorer" space telescope, which has been in orbit for about 11 years. You can see the source of the comet's name. This is a very productive telescope, which has discovered thousands of astronomical objects. Look up details in WIKIPEDIA under its name. 

At the time of discovery Neowise was a faint blob of magnitude 18, at twice the Earth's distance away from the sun. From position measurements made of Neowise C/2020 F3's orbital positions as it moved towards the Sun, a 4,400 year long orbit was calculated. By now, Neowise has been moving away from the Sun for some time, and is well past its closest approach to Earth on July 22. That means that its brightness is diminishing. The close approach to the Sun resulted in a change in the comet's orbital shape. The orbit is now longer and the comet has been recalculated to return in about 6700 years, or so (I won't wait for it).

Comet Neowise C2020 F3

This picture was taken on July 19, around 10:30 PDT with a Canon 60Da camera from our lawn next to the house. It's a 10-second exposure (f8, ISO 800). A slightly enhanced image, it is meant to show the comet better from our severely light-polluted area. It was easy to see with the naked eye. 

As the comet gets fainter, more and more telescope power will be needed to view it directly; photography, and the Hubble space telescope will be able to follow it for a longer time. By the third of August, the comet had faded to about magnitude 7, it was a faint hazy patch in my 10x50 binoculars, and I could not discern a tail. It was definitely no longer a naked-eye object. The Moon was almost full, and, in addition, the sky was somewhat hazy. Added to the light pollution in our area, this made viewing the comet less than ideal. 
 
Under similar conditions, Neowise was still visible in my 15x50 Canon stabilized binoculars in the evening (around 11pm PDT) of Aug. 9, between stars 70Virginis and 71Virginis. Directly looking at it showed a very faint, fuzzy, barely noticeable patch. Averted vision made it more readily perceived. The difficulty seeing it made for more fun to search for and trying to find it. Neowises's apparent motion is now relatively small, due to the relationship of the Earth's and the comet's respective orbits. It's like we were passed by a train, and we can see it down the track, getting smaller and smaller, but not moving sideways much.



Sunday, June 28, 2020

Is the sun getting more active?




Lunt H-alpha telescope
(Click on picture for a larger image)

Recently (Jun 28), I set up my Lunt solar-observations-only telescope (above - it contains the proper Hydrogen-alpha light filters to cut the sunlight to the correct, safe level). I was hoping to see some activity. In the last couple of years there has been very little of that. We may just have gone through a minimum of the eleven year sun cycle. The state of the solar cycle is determined by solar observatories world-wide, counting the number of sun spots over the years.

Looking through my solar telescope, the sun did show a number of prominences which had also been absent for a lengthy period. I did not see any sunspots, though. There were a few dark streaks; these are prominences which we see "from above". They are just like the ones we see at the sun's edge, but they originate on the surface away from the edge. They look darker because, as they move away from the surface, they cool down and therefore emit a little less light. This is obvious when looking at prominences at the edge of the sun, which are also fainter than the sun's surface. Here is a picture I took of the sun some years ago; it is similar to what I saw on Jun 28.

The Sun in H-alpha light
(Click on picture for a larger image)

The diameter of the sun is 104 times that of earth. If you mentally string 104 earths across the sun and compare the size of the prominences in the picture, it becomes obvious that the prominences easily exceed the size of the earth. The hydrogen gas and plasma of which the prominences are composed follow magnetic lines of force. Magnetism and its constant changes are a major part of the sun's activity. I think of the sun as a magnetized cauldron. Solar material is constantly being stirred and ejected and, if the force of the ejections are strong enough, this material will disperse into space. The earth is often in the path of such material; northern and southern lights are one effect. There are also interferences with wireless communications and power grids. Astronauts in space have to be protected as much as possible from this powerful radiation.

I think that we are finally entering the next solar cycle. The cycle should actually have a 22 year length. When sunspots appear as a pair, for instance, the leading spot (in the direction of the sun's rotation) could be magnetic north polarity. The following spot in the pair then has the south polarity. After the next minimum occurs, sunspots in the next eleven year period reverse their paired relationship polarity (south leading, north following). Nobody has a good explanation for the cause this characteristic. The next eleven-year period after the preceding two then exhibits sunspot pairs with leading north and following south polarities again. Many other solar phenomena, such as solar flares, coronal loops, solar radiation, etc. are all synchronized in some way with these magnetic changes. There are many reasonable theories, but we have limited factual knowledge about what happens inside the sun. The eleven-year cycle has been observed for many centuries (the last 400 years are quite well documented).

Over the last 10 years, NASA's Solar Dynamics Observatory, in a geostationary orbit around earth, has collected around 425 million gigabytes of data (one image every three quarters of a second, according to NASA). This effort has contributed much to an increased knowledge of how the sun interacts with earth, and the solar system.

Here is an excerpt from Wikipedia:

Solar cycle

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


If you have appropriate equipment - proper solar filters for your general-purpose telescopes - or if you follow the rules of projecting the sun onto a screen, you may want to check for the visible state of sunspots over the next years. WARNING: Never look at the sun directly without correct filters through telescopes, binoculars, or even the naked eye. Damage to the eye, possibly including blindness, can be a result, either instantly or as vision problems later in life. 

Solar observations and photography are a great way to do astronomy - you can have your regular sleep hours; no need to stay awake for much of the night. There is much information about the sun (and its effects on the earth) in the RASC's Observer's Handbook (starting on page 184 of the 2020 edition). Try it, you might like it.

Tuesday, March 31, 2020

A close, unheralded neighbour



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.

M33

M33 seems to be a satellite galaxy of the Andromeda galaxy (M31). It may perhaps be on a rebound into that galaxy. The velocities, proximity, and indications of gravitational interactions make that a possibility. A very detailed entry regarding M33 and M31 and the interactions between them can be found in Wikipedia by searching for the "Triangulum Galaxy".


Here's an excerpt from Wikipedia regarding the relationships between these two galaxies:


Relationship with the Andromeda Galaxy               

   (illustration from Wikipedia)



Triangulum on the collision paths of Milky Way and the Andromeda Galaxy. M33 appears to be linked to M31 by several streams of neutral hydrogen and stars, which suggests that a past interaction between these two galaxies took place from 2 to 8 billion years ago, and a more violent encounter will occur 2.5 billion years in the future. 

The fate of M33 was sketchy in 2009 beyond seeming to be linked to its larger neighbor M31. Suggested scenarios include being torn apart and absorbed by the greater companion, fuelling the latter with hydrogen to form new stars; eventually exhausting all of its gas, and thus the ability to form new stars; or participating in the collision between the Milky Way and M31, likely ending up orbiting the merger product and fusing with it much later. Two other possibilities are a collision with the Milky Way before the Andromeda Galaxy arrives or an ejection out of the Local Group. Astrometric data from Gaia appears to rule out the possibility that M33 and M31 are in orbit. If correct, M33 is on its first infall proper into the Andromeda Galaxy (M31).
Here is an an excerpt from a (highly recommended) Stellarium Mobile planetarium map of the sky showing the relative positions of the Triangulum and Andromeda galaxies.


Stellarium Mobile app star map.
The above excerpt shows that several different scientific opinions are stated about M33. It's obviously an object about which a number of uncertainties exit. And yet, it is less likely to be shown as an object of interest at public astronomy nights (placed best in the sky in the autumn of the year). The reason is likely because public astronomy nights are usually set in or near a city, with light pollution making M33 hard to see. Usually, the planets, the Moon, and even the Andromeda Galaxy are the showpieces.


Saturday, February 1, 2020

Are the weather gods are mad at us?


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.

click on image for a larger view

Every now-and-then, there was a break in the clouds, allowing for a short glimpse of the evening and night sky. A few nights ago, the Moon and Venus appeared very close to each other. The picture shows a similar situation exactly 4 years ago today. At that time, Mars was also near the Moon, but not this time. I looked at the recent event a couple of nights ago, through some holes in the clouds, but before I could get my camera ready, the Moon and Venus were covered up again. Let me emphasize that the apparent closeness of these two planets to the Moon is strictly a perspective effect, caused by the particular position of our Earth in its orbit around the Sun. The actual distances are in the millions of kilometres.

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

I quote an excerpt from Wikipedia:

"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

My start in Astronomy


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.

Professor Brasch's article certainly invoked a lot of nostalgia and makes me recount the many years I've enjoyed this hobby called Astronomy.
The Title Page of the Book

The picture of the simulated lunar crater which started my interest in Astronomy


Friday, August 30, 2019

Incoming comet



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


Africano will be closest to Earth on Sept 27 at around 75 million km from Earth.


Thursday, June 20, 2019

King of the sky



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

An easy target

While our winter nights in our area are cloudy for the most part, aside from the famous objects observable (the Orion nebula, say) we have some other beautiful, easily accessible star clusters available to be observed when the sky clears. One of these, an open cluster M35, in Gemini, can be seen through binoculars, and is almost overhead during that time of year, and can be found lower in the sky well into the spring, too. There is another star cluster located close to M 35, New General Catalogue (NGC) # 2158, much fainter.

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.



M35 (upper left hand quadrant) and NGC 2158 (lower right). I took this picture through a remote-control Slooh.com telescope


 Below is a map of M 35's location, a screen capture from Starry Night Pro by Simulation Curriculum:


You can also see the location of a few more objects, by no means all, which are easy to find in binoculars, and are really nice in 3 to 6 inch telescopes, at low power.

There are a number of "easy targets" in the sky at this time of year; I picked just one.






Friday, March 29, 2019

Visual aid



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).

The OLYMPUS binoculars on the left, above, have 10 power and a front lens diameter of 42 mm (fig. 2), the Bushnell and stabilized Canon (fig. 3 and 4) have 50 mm diameter front lenses. Power and front lens diameter (in millimetres [mm]) are displayed somewhere on each pair of binoculars in the form of POWER x DIAMETER, i.e. 15x50 for the Canon binoculars. In addition, the field of view in degrees is also shown.


fig. 1

fig. 2

fig. 3

fig. 4


Generally, the larger binoculars become, the heavier they are. In this group of binoculars, above, the OLYMPUS pair is the lightest, while the Canon pair is the heaviest - it contains the stabilizing electronics, as well as a battery, in addition the internal prisms which make the image appear upright. All commonly available binoculars shown are, in a basic sense, refractor type telescopes, which will normally show an upside down image. Additional optical components are needed to turn the image around once more; that delivers an "upside down upside down" image. Galileo would have given his eye-teeth to have a telescope of the quality in today's refractors and their derivatives, i.e. binoculars.

I should also mention the effect of what is called the "exit pupil" of any optical telescope, including binoculars. The exit pupil can be seen by looking at the eyepiece (the lenses where you place your eye(s) to look through a telescope). Exit pupil diameter, usually stated in mm, should match the diameter of your eyes' pupils when you use binoculars. Exit pupils are the front lenses projected by the eyepieces, and therefore contain all the light entering the front lenses (see fig. 5). If your own eye pupils, which vary their diameter depending on the brightness at which you are looking is high, your pupils contract (become smaller). If your eye pupil is smaller than the exit pupils of your binoculars, you automatically discard some of the light which is contained in the binocular's exit pupils. This is no problem when you use your binoculars during the day, but for Astronomy, you usually look at very faint objects and you want to get all the light that you can catch in the objective lenses.

There is a simple way to calculate the diameter of telescope or binocular exit pupil diameter:

DIAMETER divided by POWER i.e.    50 divided by 10 = 5mm
      42 divided by 10 = 4.2mm
      50 divided by 15 = 3.3mm

fig. 5


When you are young, your eye pupils can expand to about 7mm in deep darkness. That's why 7 x 50 binoculars are used in the navy. Most sailors tend to be young, and can make use of all the light coming into the binoculars at night. As you get older, the maximum "dark adapted" pupil diameter tends to get smaller. For instance, at age 50 you may only have a 5mm "dark adapted" pupil diameter. I'm way past that age, so my pupil diameter may possibly expand to less than that. Again, if your pupils match the diameter of exit pupil, you see all the light that your telescope or binoculars can catch. Any pair of binoculars worth their salt will also show you the larger craters on the Moon, the Galilean moons of Jupiter, brighter open and globular star clusters, movements of the planets and other interesting astronomical wonders. Much of this information is found in the RASC's Observers Handbook (free if you are a member).

As a couple of examples, there are detailed descriptions of the technical aspects of binoculars by Dr. Roy Bishop contained in the RASC's Observers Handbook, starting on page 60 in the 2019 edition. Wikipedia also contains information about binoculars.

Think of how much more light the objective lenses of telescopes and binoculars can intercept than your own pupils (50mm versus 5mm, say). It is the ratio of the disk area of a 50mm objective lens and 5 mm exit pupil you need to consider.

You can see what a great visual aid binoculars can be when using them to look at the sky at night.


Thursday, January 24, 2019

Serendipitous Eclipse

It happens very seldom that the weather gives us a break exactly when we astronomical observers want one. Usually it's the reverse: the weather is reasonable just before an interesting event. Then,  just a few hours before event time the weather clouds up, or rain starts, or snow, or any other condition which prevents us from observing is going to occur.

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.

Here is my only image, taken with a remote-control telescope at Slooh.com:



I'm always fascinated by the media's statements when they are hyping a completely normal astronomical event which repeats itself often with descriptions like "Blue Moon, Harvest Moon, Wolf Moon, Super Moon", and other mystical names.

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...

The total lunar eclipse on January 20 was indeed serendipitous.


Tuesday, November 6, 2018

Space does not look like that


J. Karl Miller wrote: please note,

Our son Derek K. Miller, along with a degree in marine biology, a diploma in non-fiction writing, had an eclectic mind, and interests in many things ranging from writing for several magazines, the Vancouver Sun, and other publications, and editing books. He also had extensive knowledge of and involvement with science, music, photography, computer technology, web page programming and administration, astronomy, and several other fields. He was among the first to make use of on-line communications, well before the internet existed in its current form.

This post is a copy of what Derek wrote in his blog about two and a half months before he died of metastatic colorectal cancer at age 41.

By Derek on February 17, 2011 6:40 PM 

Remember the end of The Empire Strikes Back, where Leia and Luke, convalescing from surgery to replace his severed hand, gaze out of the window of a Rebel spaceship at the departing Millennium Falcon, with the Galaxy (the far, far away one) spinning slowly in the background? It looked something like this:

Hubble image

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.

First of all, forget the spinning: it takes our solar system about 225 million years to make one rotation around the core of the Milky Way, so even if you were able to see the whole disk, it would take many human lifetimes to perceive any motion at all. Put another way, the last time we were at this spot in our rotation, Earth was in the middle of the Triassic period, the time of the earliest dinosaurs.

Maybe more importantly, I don't think we could see a galaxy in all its beauty that way at all, because it would probably be too dim for our eyes. Consider that all photos of other galaxies require pretty long exposures, even for sensitive equipment. The Andromeda Galaxy, which you can see in a dark sky with your naked eye as a faint smudge, doesn't show its full shape in a telescope until you collect light for at least a few minutes.

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.


If you were far enough away from a galaxy to see the whole thing, it would be even dimmer, so no matter how dark the sky, to your naked eye it would be much more a large, galaxy-shaped smudge of light (an impressive smudge indeed, but still smudgy) than the crisp, defined, and detailed colourful disks we see in photos. You might be able to determine its shape, and see the core, but it wouldn't be what Luke, Leia, R2-D2, and C-3PO were gazing at.

People are sometimes disappointed when they look through a telescope at celestial objects. Jupiter, Saturn, the Moon, and the Sun are certainly impressive, but nebulae lack the fantastic colours and flaming tendrils we've come to expect after decades of Hubble Space Telescope images. But those pictures are long exposures, often with artificial colours displaying wavelengths humans can't even see.


While those images are real, they're not what our eyes see when we look at the light directly.

Still, think about how amazing it is to do anyway: away from city lights, on a dark clear night, preferably at high altitude, you can peer up near the constellations Pegasus and Cassiopeia to find the Andromeda Galaxy, no binoculars or telescope necessary (though they'll make it yet a better experience). When you see it, you know that the light hitting your eyes started its journey two million years ago, before modern humans evolved. 


Wednesday, October 3, 2018

Getting to know the sky


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, Z├╝rich 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

Deja vu (Perseids wiped out again)

As is a tradition by now, our local centre of the Royal Astronomical Society of Canada helps out at
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.

Well, as the weather gods would have it, it turned more cloudy just as the evening approached and eventually some rain began to fall. I packed up my telescope. There was another break in the clouds about 45 minutes later and a number of people had a chance to see both Jupiter and Saturn through a couple of our other members' telescopes. Clouds then turned really heavy, and it started raining seriously towards 11pm.

After the a number of days of wildfire smoke, which covered our area during all the preceding, sunny days, and which was finally cleared out by wind from the south-west, this was a disappointment.  We are told by the park administration that fewer people than last year showed up. During the short periods when the view was worthwhile, several dozen of them came to visit our telescopes. Attendance at the talks in the tent was fortunately much higher.

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.