by Pat Browne

Astronomy Course Mississippi Valley NightSky Conservation — The Night Sky Around Us

The Local Night Sky as it appears May 3 2013 at 10 PM EDT – courtesy Earth Centered Universe

Activities will include …

• Moonlit walk to Fred Lossing Observatory (FLO)

• Dark sky observing with planispheres (no optical aid) for Constellation Practice

• Observing with binoculars

• Observing with telescopes

• Solar Observing using a special telescope filter

• Lunar Observing Techniques

• Galaxy Model Making

• Instructional Videos

• Lectures as well as Guest Lecture *Sanjeev Sivarulrasa, astro-photographer

Night Sky Conservation : ByLaw 03-62 in partnership with Mississippi Valley Conservation and the Royal Astronomical Society of Canada

In order to ensure the continued preservation of our dark skies in Mississippi Mills, we have enacted a bylaw to regulate the potential risk for light pollution from poorly designed light fixtures. All light fixtures should be shielded so that the night sky is not made bright by artificial light, and so that the stars in outer space remain visible on clear nights. This enhances public awareness of the night sky environment and encourages active research in the area of astronomical discovery such as cometary discovery.

NOW  WHEREAS, properly designed light fixtures do not emit undesirable illuminating light rays up into the night sky and thus protect the nighttime environment.
NOW THEREFORE the Council of the Corporation of the Town of Mississippi Mills ENACTS AS FOLLOWS: The Outdoor Illumination By-Law for
Mississippi Mills for the regulation and standards for responsible lighting, light pollution abatement, and the conservation of the night sky environment.

CONSIDER THIS… Our Dark Sky Site – Long History of Looking up

Mississippi Mills is the home of the Fred Lossing Observatory (FLO) maintained and operated by the Royal Astronomical Society of Canada (RASC). Located at the Mill of Kintail Conservation Area, it was built by the scientific community with high-quality optics from the National Research Council of Canada.    Thanks to the continued preservation of the night sky at the Mill of Kintail, the local dark skies have permitted the visual discovery of 5 comets, making FLO the only observatory in Canada to do this.

This is comet Garadd – captured last Spring – images courtesy P. Browne

Starship Earth within its Celestial Sphere

What we see in the Night Sky depends on:

1. Earth Rotation:Night Sky at Night Time 

Day and Night around the year As we stand on the earth looking up, 1/2 of the sphere is obscured by the earth itself. This hemisphere is bounded by the plane we call the horizon plane. During the day, the dazzling brilliance of the daytime star (the Sun) overwhelms everything else in the sky. Its light illuminates the atmosphere so that stars in the sky are not visible until the Sun sets below the horizon.

Here is a link describing what happens to our sky as we travel in our yearly orbit: A Year on Earth. 

 

 

 

 

 

 

 

Note – Small errata: The position of the sun on vernal and autumnal equinoz is 1/2 point on the graph midway up the y-axis – not the cross-over point on the Analemma

2. Our Latitude on earth

This sets our horizon, and what is above or below it when we look up at night. Objects below the horizon cannot be viewed. Certain celestial objects remain permanently below our horizon.

 

 

 

 

 

 

 

 

3. Earth Orbit:

The sky in different times of year: Because our orbit around the sun changes our direction in space, it changes what constellations are visible when the sun is below the horizon As the earth orbits around the Sun in the year, the nightsky will contain different objects, different constellations.

 

Courtesy R. Dick, The Celestial Sphere, Starlight Theatre

Looking Out Into Our Night Sky with the help of the Celestial Sphere

We are all traveling together through space on a giant starship – our home planet Earth. From this starship we look out in various directions at the universe that surrounds us – at our nearby neighbours like the moon, and planets, and beyond to the more remote light sources which originated in galactic stellar material. The galaxy we live in is the the Milky Way, containing more than 200 billion stars. All of these celestial objects form a a majestic backdrop to the velvet canvas of night – the period each day when our spinning planet carries us away from the daytime star in our sky, the Sun, so that we can gaze at the universe beyond.

First we examine the closest objects to spaceship earth – the other 7 satellites of the Sun. These objects are so relatively close that the earth’s orbit with respect to their orbit trace moving trajectories in space night after night.

Next we turn our attention to the constellations that we see at this time of year. A constellation is different from an asterism . Constellations are groupings of stars that are recognized as fixed star patterns on the celestial sphere. A set of 88 officially recognized constellations completely covers the sky. Many constellations are composed of faint stars forming random patterns. The brightest stars help us delineate their form. But many still require our imagination.

Next lecture we will start to study systems of stars, star clusters that are found within constellation boundaries that we will learn to recognize. We use constellations as a set of featured patterns that guide us to finding our binocular or telescopic object, such as a star cluster or a galaxy. Everything seen in the form of stars in a constellation, or star clusters is found within our own Milky Way galaxy; however we can look out and see other galaxies, particularly in the spring time because our pointing direction in our orbit at this time of year projects outward away from the disk of the Milky Way galaxy .

Our Nearest Neighbours –Our Solar System : Planets, Comets and Asteroids

Wanderers around the Celestial Sphere … they move night after night in relation to Earth

The Planets and Cometary objects in our Solar System are visible to us when their orbit takes them away from the glare of the sun into our night sky: Hence we do planetary and comet observations when they appear above our horizon as they travel along the ecliptic (or, for comets, on their eccentric heliocentric path) after the Sun has set below the horizon. In different years, we will see planets at different times. Their position is not fixed on our celestial sphere. They are wanderers, and may become morning or evening ‘stars’ depending on their proximity to the Sun.

12 Special Constellations: The Zodiac

The planets run along the path of the ecliptic and the constellations along this path form the Zodiac: These 12 famous constellations are seen in different seasons:

The Ram, the Bull, the heavenly Twins, and next the Crab, the Lion Stands, the Virgin and the Scale,

Scorp, and Sag the Old Sea Goat, the Man who doth the water Tote, and the fish with the Glittering Tail

>———–Winter———Spring—————- Summer——————–Fall—————->

Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius, Pisces

Here is an animation of the planets as they dance around the special path of the ecliptic. Saturn and Mercury and Venus and Jupiter are shown along the ecliptic path . Click on the image to see the animation.

Our Solar System:  Celestial Motion of the planets along the plane of the ecliptic relative to Earth:

All planets and the Sun appear to move Eastward with respect to the background stars day after day.

The planets fall into two groups depending on their relative distance

• Superior : Sun-Earth-Planet

•  Inferior Planets (between Sun and Earth)

              Mercury and Venus are the inferior planets.

These planets do not travel beyond Eastern and Western Elongation. Elongation is the angle between the Sun-Earth line and the Sun-Planet line. When an inner planet (Mercury or Venus) attains maximum elongation, we refer to it as Greatest {Western or Eastern) elongation. At greatest Eastern Elongation, the inferior planet appears higher and higher in the Western Sky and appears as an evening ‘star’. In this configuration it follows the sun and is visible after sunset. It then moves closer to the horizon at sunset as it sweeps through the sun, disappears into Inferior Conjunction and reappears as a pre-dawn morning ‘star’, preceding the sun (west of) before sunrise so we can see it while still dark.

Superior Planets (beyond Earth) Superior planets are:

• Mars

• Jupiter

• Saturn

• Neptune

• Uranus

Superior planets exhibit retrograde motion as they approach opposition. Opposition occurs when the angle Sun-Earth-Planet is 180 degrees, and the planet is on the opposite side of the sun. The farther the planet lies from the Sun, the slower it moves around the Sun. When the Earth and another planet pass each other on the same side of the Sun, the apparent retrograde loop occurs. This is an observational phenomena, not an actual loop in space. It is caused by the relative angular speeds of the Earth and the outer planet. This shows up as a change in direction from one night to the next when we make our observations.

Here is an animation of Mars (also a superior planet) as it approaches opposition. We observe the motion as West to East (R-L) with respect to earth until we come closer to opposition.Then for a few days, the planet goes into retrograde (looping East to West, back to West to East) as the earth in its closer orbit to the Sun speeds past it. Retrograde motion happens when the angular speed of outer planets appears to slow down when planet and Earth are moving in the same direction, around the sun, and the earth ‘overtakes’ the planet, like a faster car on a highway.

Beyond the Close Objects of the Solar System to … Our  Distant Neighbours – Stars and Constellations on the Celestial Sphere

With a 3-dimensional Celestial Sphere we can peer out from the inside and find our stars for a particular time of year .The little globe of the earth is placed to orient the observer according to the ring of the local horizon as shown by the horizon ring. Once, the Latitude, Longitude, and Date and Time of the observer are arranged, the appearance of the constellations are fixed, and the stars are ‘observed’ looking from the inside out.

Our Distant Neighbours – Stars and Constellations on the Celestial Sphere

With a 3-dimensional Celestial Sphere we can peer out from the inside and find our stars for a particular time of year .The little globe of the earth is placed to orient the observer according to the ring of the local horizon as shown by the horizon ring. Once, the Latitude, Longitude, and Date and Time of the observer are arranged, the appearance of the constellations are fixed, and the stars are ‘observed’ looking from the inside out.

We can also use a 2-dimensional aid , a Planisphere to determine what’s up in the sky tonight:

Planisphere – Plan your Sphere!

Looking at the Southern Horizon On May 3 at 9 pm for a Latitude of 45 degrees

Constellations in May: Southern Horizon – on or near your meridian

• Leo (with Galaxy Triplet), Virgo, Cassiopeia, Draco, Corvus

Constellations in May : Western Horizon – about to set (winter constellations)

• Setting in the West are Gemini, and Orion

Constellations in May: Eastern Horizon – preview of summer

• Rising in the East is Hercules and Ophiuchus

Starhop through the Constellations “Follow the Arc to Arcturus … Speed down to Spica in Virgo”

We can use starhopping techniques to locate a galaxy! Locate M51, the Whirlpool Galaxy just below the handle of the Big Dipper

The celestial sphere presented in this lecture is set for May 3 after 9 PM

• Saturn is visible and Jupiter is just about to set. When you observe them in a scope or even binoculars, notice the configuration of Jupiter’s moons. They change every night.
• Bright stars can be identified such as Regulus in Leo – which is also a multiple star system
• Open Star Clusters such as M44, the magnificent Beehive cluster – visible naked eye as a swarm of stars!
• Globular Star Clusters such as M53 containing tens of thousands of stars; these lie scattered throughout the sky
• Galaxies and Clusters of Galaxies (in Leo and Virgo) are very abundant as we are looking out of the plane of the disk of our galaxy!
• Next time we will see the celestial sphere has turned a bit. We will notice this as we look up!

Astronomical Objects found in the Catalogs

Astronomical observers have a wealth of objects to observe and study. Contributions to scientific data are often made by amateurs. The planetarium program ECU includes data from nearly 20 astronomical object catalogs printed in the Observer’s Handbook. These include the following:

 Colored  and Double Stars

Open Clusters -situated within the Milky Way – Patches of dense star groups – Like the Beehive Cluster, M44

Globular Clusters – 10,000s of suns, not resolvable as point light sources

Galaxies – like M51, the Whirlpool galaxy

The two catalogs we will use for observing will be the

• Messier Object Catalog http://me ssier.seds.org/data2.html
• David Levy’s Deep Sky Gems http://kingston.rasc.ca/Observing/deepsky.php

The Messier objects are found on many Star Charts, and the David Levy Deep Sky Gems are embedded in the program Earth Centered Universe – Observer’s Handbook Edition.

Astronomical Cataloging … (A historical note)

What’s the M in M1, M2, … M110?

This is a sketch of what the observer saw through the eyepiece when he pointed his telescope at M1, or Messier Object 1, the Crab Nebula in the winter constellation Taurus. This is a Supernova Remnant!

The  great contemporary Canadian comet hunter, David Levy writes…

“Fuzzy objects that are not comets lurk all over the sky. They are beautiful to watch, but for people who search for comets they can be viewed as an inconvenience; comet discoverer Leslie Peltier called them “comet masqueraders.” At the end of 1758, Charles Messier found a fuzzy patch around Zeta Tauri. As he studied it from hour to hour and from night to night, he found that the faint fuzzy object stayed plastered> to the sky; even though it looked like a comet, it never moved like a comet Deep Sky Objects, David Levy, p. 24

As the Earth Turns – Tour of the Night Sky – May 3 2013, after 9 PM EDT

When planning your observing session , start with the things that are going to set first – Westward HO! Below is the ECU view of the celestial sphere showing the western sky,You can see this on your planisphere. But your planisphere does not show the planets because they change from year to year. ECU can program the planets in…

Celestial Wanderers: Planets and Comets

• Jupiter, nearly set…
• Saturn Rising
• Comet PANSTARS/C2011 L4 – near Cassiopeia

Night Sky West on May 3 2013 – Late Winter, early Spring Clusters

Returning back to the May 3 Night Sky Overview Map, we will visit tonight (or a night that is clear and moon-less)  …

Night Sky South in May: 2013 – Galaxies and Globular Clusters