What is a Planet?

There has always been some talk about redefining what a planet is.  The link below gives a brief summary of the debate that erupted in 2017.

http://www.astronomy.com/news/2017/03/is-it-time-to-restore-plutos-status

The word planet comes from the Greek word planan which means 'wander'.  Ancient observations showed that these objects in the sky would wander around compared to the background stars.

According to the International Astronomical Union (IAU) Q&A section it states in plain terms:

A planet is an object in orbit around the Sun that is large enough (massive enough) to have its self-gravity pull itself into a round (or near-spherical) shape. In addition a planet orbits in a clear path around the Sun. If any object ventures near the orbit of a planet, it will either collide with the planet, and thereby be accreted, or be ejected into another orbit.'
The exact wording of the definition is given below:

A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

 A dwarf planet is defined as the following:

'A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.'

This would put Pluto in the category of Dwarf Planet.  Four other recognized dwarf planets are Ceres,  Haumea, Makemake and Eris.

Pluto (Image Credit: NASA)

The planets as everyone knows are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.  Most of them have satellites which we call Moons.  Some Moons are larger than the dwarf planets but they do not fit the criterion is not a satellite and therefore remain categorized as such.  As an interesting fact, the largest Moon in the Solar System, Ganymede, is actually larger than Mercury.

All of the 8 planets are visible from your backyard.  Mercury, Venus, Earth, Mars, Jupiter, Saturn, and if you have really good eyesight, Uranus are visible with the naked eye.  Neptune will require optical assistance as it is fairly dim.  The image below contains some photographs I have taken of the planets and the Sun.  Uranus, Mars and the Earth are the only photographs below that I did not take.

Solar System

Ceres and Pluto can be viewed from your backyard.  Pluto requires a significant skill and effort as it is on the cusp of limiting magnitude for most amateur telescopes.

Ceres (Image Credit: NASA)

Keep an eye on our Facebook Page for updates as to when you can easily see each planet!

2017 Imaging Night #1

Last night (March 19, 2017) was a remarkably clear night and I took the opportunity to take some images.  Unfortunately the grass still had ice on it so I can to put my imaging scope on the deck.  The house blocks Polaris (The North Star) so I was unable to get perfect polar alignment and thus suffered from drift in some long exposures.  I also did not use an autoguider because I still need to learn how but it would have remedied some of the drift problems.

The basic procedure of what I did is written below.

1. Setup tripod and mount and pointed the polar axis to some point behind my house where I thought Polaris was.
2. Put the OTA (Optical Tube Assembly) onto the mount.  My 2 year old imaging supervisor ensured it was done correctly.





Supervisor



3. Installed straight through finderscope and red dot finder on top of the OTA.
4. Balanced the OTA with a 22lb weight.
5. Aligned the system using Rigel and Betelgeuse, calibrated with Sirius.
6. Installed DSLR camera using a 2" prime focus adapter in the eyepiece holder.
7. Used Sirius to obtain focus through the camera.
8. Imaged M46, M47, M93, M41, M35, M36, M37, M38, M42, M43 with exposure times between 5s-35s depending on the object

It was apparent in some of the longer exposures that correct polar aligned and autoguiding would have helped me a lot.  Shown below are some of the images taken last night.

M42 - The Orion Nebula(below) and M43 - De Mairan's Nebula(above)

Longer Exposure (M43 is more clear but stars are blurred)

M35 in Gemini

I will update the previous Messier blogs with their corresponding images.  A Topic Contents box has been added to the main page of the blog so you can check out the latest in each category.  If you are new to the blog feel free to look through some of your favourite constellations or deep sky objects.

Topic Contents

The weather is a lot cooler and cloudy today so there may not be any observing or imaging.  However, I will try to update the images on the Messier pages.  Clear skies!

Messier Objects - M46

After the major cold snap and a cloudy warm front the weather was ideal for astronomy last Thursday evening.  I spent some time in the southern constellation of Puppis.  Puppis represents the poop deck of a giant ship in the sky.  The poop deck is the highest point on a ship and it typically covers a cabin; it is not where the latrines are kept.  Carina and Vela are also constellations that create the former overlarge constellation of the Argo Navis.  From the latitude of Calgary we are unable to see the complete constellation of Puppis but the northern reaches are definitely accessible.

The Milky Way traverses Puppis and thus there are many open clusters contained therein.  Messier 46 and Messier 47 are two of the largest clusters and are easily seen through binoculars and are spectacular through a telescope.

To find M46 I put my red dot finder on the sky's brightest star: Sirius.  I then moved the telescope eastward between γ and ι Canis Majoris until I found a dense cluster with many stars.  I estimated that there are several hundred stars making up the cluster.  My estimate of the size was 22' and the accepted value is 27'.  The faint stars in the outer edge of the cluster probably caused me to underestimate the size of it with a 8" aperture telescope.

M46 Observation Record

An interesting thing about M46 is that it contains a planetary nebula and a preplanetary nebula.  The planetary nebula NGC 2438 is not part of the cluster but aligned in the sky with it.  However, the preplanetary nebula known as the Calabash Nebula or Rotten Egg Nebula (due to its high sulphur content) is likely part of the cluster.  It shares the same distance, radial velocity and proper motion as its fellow members.

At the observatory last month I took a real good look at M46 and think I may have seen NGC 2438 as a faint fuzzy patch on the outer edge of the open cluster.  I was not able to see that from the city probably due to the light pollution.  I am hoping to image this cluster with my 11" and see if I can resolve NGC 2438 with longer exposures.  Also, as I image the Messier objects I will be able to fill in the blank image spot of my observation records!

The skies are supposed to be great this week, so if the wind abates and the clouds stay away there will be plenty of great things to see.  The RAO is having an open house on March 25 and there will be telescopes setup in Fish Creek Park on April 1.  These are great events to get the family out to see some amazing sights above us!

Lunar X and Lunar V

Every lunar cycle (29.5 days) the lighting on the Moon is just right that an X and V seem to appear underneath the terminator.  This only occurs for few short hours per cycle at certain locations on the Earth.  I was looking through the dates and times it was and is supposed to happen and noticed the date November 6, 2016 was good for Calgary.  I went through my photo database and noticed I was imaging the Moon that evening.  I had accidentally muddled my way into taking a picture of them.

Lunar X and Lunar V

An external link to a paper written on this topic by a fellow RASC member in Halifax is provided below.

http://wasociety.us/Lunar-X.pdf

The Lunar X and V are visual 'objects' created by what is known as the clair-obscur effect.  It is an interplay between light and shadow creating unique effects on a surface.  There are a number of these that you can see on the Moon during a given cycle.  A list is provided at an external link below.

http://the-moon.wikispaces.com/clair-obscur

You will need a good set of binoculars as a minimum to see this effect.  If you would like to see the Lunar X or V this year a list of the 5 remaining dates and times for Calgary in 2017 is provided below.

April 3, 16:21

June 1, 15:36

July 30, 14:33

September 27, 15:25

November 26, 18:46 MDT, 17:46 MST (will the savings time law be passed?)

Good luck hunting the sky!

2017 Week 12: (March 19-25)

The weather has certainly warmed up but we've had many clouds in the night sky.  I only saw a star here and there this week and am hoping for better skies in the week that follows.  There was a very bright iridium flare last Wednesday evening that shone through the thick overcast clouds.  I found it remarkable that a satellite could shine so brightly that it could penetrate the cloudy sky.

Date	Event
Mar 20	Saturn 3°S of Moon
Mar 20	Vernal Equinox
Mar 20	Last Quarter
Mar 25	Venus at inferior conjunction

Next week has the equinox where the Sun cross the celestial equator to begin Spring.  This also happens to occur a few hours before the Moon is at last quarter.  The weather is supposed to be great for observing.  There are few clouds and warm temperatures forecast for next week.  I am hoping to use this opportunity to get the equatorial mount out to update my Messier pictures.

Venus will be at inferior conjuction on March 25.  This means it crosses the same celestial longitude (Right Ascension) as the Sun.  However, the way the orbital plane is oriented, Venus will pass approximately 7° over the Sun.  If you can catch it right you can see Venus set after the Sun and rise before the Sun the next morning.  You may even catch Venus at its new phase, similar to a New Moon.

This next week might be a good opportunity for trying to track down our Solar System's smallest planet -- Mercury.  Mercury will be visible in the western sky for a few weeks centered on April 1.  It will be at what is known as its greatest elongation East.  This means it is at its furthest distance East of the Sun in its orbit.  Mercury tends to not be visible most of the time because the Sun drowns out the light of the planet.  However, when Mercury is at its furthest point away from the Sun it gives us the opportunity to glimpse it.  If you can find Mars close after sunset look down and you should be able to see Mercury.  If you live in McKenzie Lake, I would recommend a walk to the Bow River ridge right after sunset.  Wait until the twilight clears and see if a point of light appears above the horizon.  You may have found Mercury!

Another important thing to look for in the sky is Comet 41P/Tuttle-Giacobini-Kresak.  It will be in the scoop of the Big Dipper from March 22-24 at around magnitude 7.2.  It should be able to be seen through modest binoculars.  Scan inside the scoop with your binoculars and you may see a fuzzy patch of green light.  That will be your comet!  Don't fret if you are unable to find it.  It will get brighter up until April 2.  For more information, please see my previous blog post on the comet below.

http://simonjastronomy.blogspot.com/2017/03/comet-alert-41ptuttle-giacobini-kresak.html

In closing this post I would like to celebrate the fact the clouds parted this evening for a good thirty minutes of observation time.  It became too humid and my optics started to dew up so I had to pack it in early.  However, I was able to hunt down four Messier objects in and around Canis Major and Puppis.  Updates on these objects will be provided in blog posts next week; hopefully with pictures!

Please enjoy the weather and clear skies.  If you have any questions about anything you see please contact me and we can have a discussion!  Good luck and clear skies!

What is an Iridium Flare?

I'm sure at some time or another you have seen a satellite transit the sky above your head.  However, what would happen if the satellite was angled just right such that it reflected the Sun back down to you.  This is what is known as a satellite flare.  The satellite will brighten significantly, potentially becoming brighter than a crescent moon.

There is a group of satellites (called a constellation) that are controlled and have easily predicted satellite flares.  These satellites are the Iridium Satellites.  The original plan was to have 77 of them in orbit (77 is the atomic number for Iridium) but only 66 were necessary to be operational.

The following site is a good resource for locating iridium flares from your location.

http://www.heavens-above.com/IridiumFlares.aspx

You can also download the Heavens Above application for your mobile device that will provide you with all the information necessary to see a flare and other controlled satellites; even the space station.

Iridium flares typically occur several times an evening and they are VERY easy to see.  Using the app, find the place in the sky where it will occur and start watching a minute before it is due to flare.  You should see a dim satellite nearing the flare point all of a sudden become the brightest object in the sky.  You may think it is a plane, but it can be even brighter.  An image of a flare is shown below.

Iridium Flare

On Wednesday March 15, 2017 at 9:02pm in Calgary there will be a very bright flare between the heads of Gemini and the head of the lion of Leo.  See the map below for details.  If you miss it don't worry as these are a common occurrence.

-8.4 Iridium Flare, Calgary, AB March 15, 2017, 21:02

However, in the near future these satellites will be going offline and replaced by a newer fleet.  A news article on this is provided below.

http://news.nationalgeographic.com/2017/01/skywatching-iridium-flares-spacex-satellites-space-science/

I would suggest grabbing the Heavens Above application and go outside to catch one of these before they become extinct.  If you can photograph one that would be amazing.  I will try for the bright one tomorrow by placing a wide-angle between the two heads and start a long exposure.  Good luck if you attempt to see it!

Binoculars - What should I look for?

I have mentioned binoculars many times throughout these posts and I thought it would be good to discuss them more.  An introduction to telescopes was provided last month.

Telescopes - What should I look for?

I can not stress enough, binoculars are amazing for astronomy.  A telescope is not necessary to observe a lot of really amazing things in the night sky.  Binoculars are relatively cheap and very portable.  A lot of people already own a pair of binoculars and there is nothing required to adapt them for celestial viewing.  Even with the smallest 7x35 you can increase the number of stars you see by 30.

The first thing to understand about binoculars is its magnification and aperture.  Most binoculars are marketed as 7x35, 10x50 etc.  The first number represents the magnification and the second number is the aperture in millimeters.  As with telescopes, the larger the aperature, the more light you will be able to gather.  This is helpful for finding dim objects.  Also note that the higher the magnification, the higher your hand shakes are magnified, so you will want to look into tripods or mounts.

The field of view is also an important factor when purchasing a set of binoculars.  Typical binoculars can range anywhere between 3° and 8°.  Consider the target you would like to look at to determine how wide you want your field of view.  Most deep-sky objects are under 2° so you should have no trouble.  However, some common asterisms can be much wider and low power binoculars should be used.

There are many publications that can be found at your local library specifically for binocular astronomy.  Most astronomy magazine publications have a monthly article dedicated to the many wonders you can see with binoculars.  A telescope's narrow field of view can be a detriment in many cases.  You can purchase quality wide-field eyepieces for your telescope to see wider views but they can sometimes run you up $1000 a piece.

Another thing to consider is image-stablised binoculars.  You can look through your binoculars and then press a button and everything becomes still.  These are amazing.  However, these are also expensive and will chew through your wallet and batteries.  If you really want to try them out I would recommend attending an observing party or astronomy open house.

Let's talk about small binoculars (<50mm aperture)

They are very portable and can fit in your glove compartment, handbag or a small luggage compartment in your suitcase.  These are excellent to start out in astronomy and they usually have a very wide field of view.   This makes it exceptionally easy to hop from star to star in your favourite constellation.  They are also quite useful for learning the sky around a telescopic target that you might try to search for later in the evening.

7x35 Binoculars

Medium binoculars (50-100mm aperture)

I have a 15x70 set that I use every night it is clear.  With medium binoculars you are bordering on stability issues.  They may get heavy after awhile and you find yourself trembling.  You can remedy this by lying on your back and resting them against your eyes or gripping them closer to the objective lens.  Most medium binoculars can also be attached to a tripod but, of course, forces you to carry a tripod around with you.  The field of view is typically narrower so more sky experience is necessary for finding a specific target.  That being said, I've found many star clusters and nebulae with my binoculars and their sharp focus is amazing.  You can pick out individual craters and maria on the Moon and even see moons of the Jovian planets.  My set are shown below.

15x70 Binoculars (4.4° Field of View)

Large binoculars (>100mm aperature)

Stability and portability are major drawbacks of large binoculars.  You will almost definitely have to get a tripod or mount to attach your binoculars.  A 100mm set is like lifting two 4" telescopes to your eyes every time you want to see something.  The field of view is relatively narrow and closes off certain asterisms that pop out with a smaller set.  However, deep-sky objects are absolutely amazing and clusters are well defined.  Tight double stars are easily separated, cloud bands on Jupiter pop into view and you can even see the rings of Saturn.  Taking a pair of these (with a mount) to a dark site would be amazing.  I've seen some sets that are bordering on 50lbs, those would be fun to look through.

100mm Binoculars

You can even get carried away and build an observatory around binoculars as in Arizona.

Large Binocular Telescope