Know the Constellation - Canis Major

Last time we checked out the Orion constellation. Now its time for Canis Major. Canis Major is located in the southern celestial hemisphere. The name literally means, "The big dog". Canis major, beside the much smaller constellation, Little Dog, is commonly portrayed as accompanying the legendary hunter, Orion. It contains largely of young blue stars. The most important stars within the constellation are, Sirius, Adhara, Wezen and VY canis Majoris.

Sirius, the brightest star in the night sky, is a Spectroscopic Binary star. It is twice as bright as Canopus, the next brightest star. It appears bright because of both Sirius's intrinsic luminosity and proximity to Earth. Sirius is twenty five times additional luminous than the Sun, however features a considerably lower brightness than other bright stars like Canopus or Rigel. Sirius system is one of Earth's near neighbours.It is approx. 9 light years from Earth.The sky location for Sirius is : RA 06h 45m 08s, Dec -17°16' 42".

Know the basics of sky gazing, Sky Gazing for Beginners - Part I

Adhara is a star in Double system. It is the second brightest star in the constellation. The name Adhara came from Arabic, meaning "Virgins". It is one of the brightest known extreme ultraviolet sources in the sky. About 4,700,000 years ago, Adhara was only 34 light years from the Sun, and was the brightest star. It is approx. 405 light years from Earth. The sky location for Adhara is : RA 06h 58m 38s, Dec -29°01' 41".

Wezen is a yellow-white supergiant variable star. It is approx. 1607 light years from Earth. The sky location for Wezen is : RA 07h 08m 23s, Dec -27°36' 25".

VY Canis Majoris is a single star categorised as a semi regular variable with an estimated period of 2,000 days. If placed at the position of Sun, VY Canis Majoris's surface would extend on the far side the orbit of Jupiter, though there's still sizeable variation in estimates of the radius. It is approx. 4892 light years from Earth. The sky location for VY Canis Majoris is : RA 07h 22m 58s, Dec -25°46' 03".

Star Gazing for Beginners - Part III

Eyes on the Sky

If you haven't gone through the first and second parts, please have a look on it, Star Gazing for Beginners - Part I, Star Gazing for Beginners - Part II

Transcript:

Hi I’m David Fuller from the “Eyes on the Sky” video series. In this last Stargazing Basics video, we’ll learn how to easily measure distance in the sky, so you can find constellations or objects more easily either naked eye, with binoculars or telescopes. In our first video, we learned that a line called the meridian splits the sky into equal halves, from north to south. If we were to place a giant protractor in place of that line, it would appear as if the sky was 180 degrees from horizon to horizon. Although space is actually infinite, our eyes make the night sky appear like a “half sphere,” so for all practical purposes, it’s easier to think of the sphere. And though a sphere should technically be measure in radians, degrees is a concept people understand more readily and works for our purposes. So horizon to horizon is 180 degrees – that’s easy enough. And if we measured another large distance, from horizon to zenith, that would produce a right angle, or 90 degrees. Still pretty simple, right? But to measure smaller angles than that, we need a measuring tool. A ruler doesn’t work, because that would be for linear measurement, and holding a protractor to our eyes is a bit impractical. So what to do? Easy: Use your hands!

Check this out: Hold out your hand at arm’s length. Now spread your thumb and pinky as far away from each other as possible. If you look across your thumb and pinky, that distance is approximately 25 degrees. Don’t worry – this works for almost everyone. Don’t believe me? Look for the Big Dipper in the night sky. See the last two stars in the “Bowl” of the dipper? Draw a line through them, from the “bottom” of the bowl towards the top. Now hold your hand at that top star, along that line. The other side of your outstretched hand should be near Polaris, the north star, because that distance is NEARLY 25 DEGREES. But sometimes we need to measure smaller distances than 25 degrees. This time, hold up your forefinger and pinky, and stretch them out. The distance across them is about 15 degrees. This is about the distance from Orion’s belt to the star Aldebaran – this way – or the star Sirius, going this way. You can find these stars in the winter sky.

Img Credits : squarespace.com

For another smaller tool, hold up your fist. Across the top of your fist from side to side is about 10 degrees of sky. We can ‘calibrate” that by looking at FIND A GOOD CIRCUMPOLAR CALIBRATION. Two split that in half, now hold up these three fingers – this approximates 5 degrees of sky. Those two stars at the end of the Big Dipper are about 5 degrees from each other. Hold up your hand and see if your fingers match that. And lastly, the one degree tool. Simply hold up your pinky! This one amazes many people, because the actual angular distance across the Full Moon is only half of a degree. So holding your pinky at arm’s length, you can cover the WHOLE Moon! Of course, mixing and matching these can help you find even more – two hands like this can measure halfway across the 90 degrees of horizon to zenith, approximating 45 or 50 degrees or so. Use other combinations to create 30, 35 or 40 degrees, just by using two hands. 

But how will you know how far an angle is in the sky from a star chart? The declination lines will tell you degrees, but only in that direction. Try downloading the “Skymaps” all sky star charts each month. These charts are about 180 millimeters across. Though not terribly useful at the edges, as the sky diagrams are “stretched” there, you can use a simple ruler with millimeters on it to measure approximate angular distances in the sky, helping you “hop” from bright stars or well known constellations, to dimmer ones. Give it a try – it’s really easy, and works for just about everyone. Thanks for watching; I’m David Fuller. Keep your eyes on the sky and your outdoor lights aimed down by using dark sky friendly lighting fixtures, so we can all see, what’s up. 

Know the Constellation - Orion

Orion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. Orion got its name from Greek Mythology. The story says, Orion was a giant hunter whom Zeus Placed among the stars as the Orion Constellation.

The brightest stars in Orion are Rigel and Betelgeuse. 

Located in the constellation Orion, Rigel is a Pulsating Variable Star. It is the brightest object in Orion,Rigel is approximately 863 light-years from earth. The sky location for Rigel is : RA 05h 14m 32s, Dec -09°47' 54"

Know the basics of sky gazing, Sky Gazing for Beginners - Part I

Betelgeuse is a Semi-regular Pulsating Star with distinctly reddish-tint. It is the second brightest star in Orion. It is also known by Betelgeuse's Bayer designation Alpha Orionis and is the ninth brightest star in the night sky. It is approximately 498 light-years from earth. Betelgeuse marks the upper right vertex of the Winter Triangle and center of the Winter Hexagon. Betelgeuse is expected to explode as a type II supernova. The sky location for Betelgeuse is : RA 05h 55m 10s, Dec +07°24' 26"

Credits : astrobob.areavoices.com

You can locate Sirius, the brightest star in the night sky, by using the belt of Orion. The belt points South East directly toward Sirius. Sirius is in the constellation of Canis Major and it is the fifth-nearest known star with a distance of just 8.7 light-years from earth.

Star Gazing for Beginners - Part I

Eyes on the Sky

Transcript:

Hi I’m David Fuller from the “Eyes on the Sky” video series. Let’s look at Stargazing Basics, starting with understanding directions in the sky. Most of us are already familiar with the cardinal directions of north, south, east and west.

Those can be further split into 16 sub-directions, like southwest or south-southwest and south-southeast. But all that really tells us is what direction we are looking from our location; and at best, really only in areas close to the horizon. 

Not only that, just as the Sun rises in the east and sets in the west, the stars in the night sky also rise in the east and set in the west over the course of the night. So how do we discuss other aspects of the sky? Let’s start with those cardinal directions again. If we split the sky exactly in half, from north to south, we would have a line bisecting those halves. That line is called “The meridian.” This line never moves, because it always divides the sky from north to south. Now if we locate the exact halfway point of the meridian, we are looking directly overhead, and that point in the sky is known as the zenith. So what other “locating features” in the sky are there? 

Although we don’t see stars during daytime, the imaginary line in the sky that the Sun traces as Earth revolves around the Sun is called the ecliptic. Since the planets in our solar system orbit our star largely on the same plane as each other, the path of the planets in the sky closely follows this line of the Sun. This line appears lower in the sky during the summer, and higher during the winter months. So close to – or sometimes right on – the ecliptic is where we will always find naked eye and telescopic planets in our solar system. Now keep in mind that the Sun doesn’t actually rise or set; what is actually happening is the Earth is rotating – we just don’t feel that rotation, because we humans are just along for the ride. So as Earth spins, imagine if you were standing at the North Pole, and looked straight overhead (when it was dark). The stars would appear to spin around a circle, with the axis of that circle at the zenith – the point overhead we talked about earlier. That point in the sky around which the stars rotate is the celestial pole. Of course, you likely won’t ever see it like that, because no one lives at the North Pole. So as we move downwards in latitude in the northern hemisphere, that point in the sky around which the stars rotates will move down towards the northern horizon. If you’re in the upper latitudes, it will appear higher; the nearer you are to the equator, the closer that point is to the northern horizon. If you’ve every looked at a globe with latitude and longitude lines on it, then you can probably imagine pretty easily our next set of markings in the sky: The celestial sphere.

The celestial pole is like a spot on a basketball where the lines meet, and where a good basketball player can make it spin. To locate objects in the sky, we use coordinates like on Earth, but instead of latitude and longitude, we projects those lines out into space as if they were on a transparent sphere surrounding Earth, and these are called Right Ascension and Declination. Right ascension is easy to remember: Face north for a moment. If the Sun rises in the east, which side of your body is that? The right side. So the sun, “ascends” from your right – or Right Ascension. These are like the longitude lines on Earth, that start at one pole and run to the other in equal spacings. These are listed in “hours” and “minutes”, and the Zero “Hour” for Right Ascension begins in Aries the Ram That’s easy enough, yes? And declination is simply the number of degrees away from the celestial poles – so the degrees from the celestial pole to the celestial equator is 90 degrees, just like the degrees from our North Pole to the equator. With me so far? Great! 

Lets review these: quickly: North, East, South, West never change. The meridian splits the sky into two half from north to south The Zenith is directly overhead The ecliptic is the path the Sun takes in the sky, along which the planets large follow. The celestial pole is the spot in the sky around which the stars appear to rotate as Earth spins. The celestial sphere uses similar coordinates as longitude and latitude, but are called Right Ascension and Declination Not hard at all, right? Okay, right ascension and declination may take a bit to get used to, but the rest should be pretty straightforward. In the next, I’ll explain how to understand the difference in brightness between objects in the sky. Thanks for watching; I’m David Fuller. Keep your eyes on the sky and your outdoor lights aimed down by using dark sky friendly lighting fixtures, so we can all see, what’s up.

Star Gazing for Beginners - Part II