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Here is an article about Stellarium, that appeared on today’s issue of Kannada daily Samyukta Karnataka (9/27/2012). Click on the image for a enlarged view. My article is at the bottom of the page:
If the full page view is hard to read, you may choose to click on the following image, for a better resolution, but without the graphical elements:
(I wrote this article last year for ಅರಿವಿನ ಅಲೆಗಳು by Sanchaya).
By the way, I did not even notice another year has gone by for my blog. Surely, this has been the most inactive year for me on ಅಲ್ಲಿದೆ ನಮ್ಮ ಮನೆ!
Ever wondered what would you see on a Full Moon day, if you were on the Moon?
Answer: It depends.
It depends on where you are standing on the Moon. If you are on the far side of the Moon that is always turned away from the Earth, then you would be standing in the lunar night. Pretty much you’d see what you would see from Earth in a dark night sky. Except that there won’t be the Moon. And of course, there won’t be Earth too, because you are on the far side.
If you are on the near side of the Moon that always faces the Earth, then it is your daytime! So you would see the Sun, and you’d see a New Earth – which actually can’t be seen, unless of course, it is a solar eclipse occurring at your location on the Moon (which in turn means it is a lunar eclipse for your friends on the Earth).
Since there is no atmosphere, and no dispersion of light, you could see stars and planets, if you can somehow block the sunlight!
Stellarium makes it easy to visualize that. Here is a screenshot from a time few hours from now, when the Moon appears full for earthlings.
You can see the “New Earth” pretty close to the Sun, but not close enough to cause an eclipse. As an aside, there are three planets, and parts of three constellations of the zodiac visible in the screen shot. Click on the image for a better view.
If you are one of the millions of people who believe in their daily horoscope, or even if your are casually curious about it you’d have been hit with this news couple of weeks ago. For some true believers, this news has been heartbreaking to hear that the Sun was not even in the constellation that they thought their sign was when they were born. If you were wondering how this drastic change in the Sun signs came about, read on.
You need to get familiar with a few technical terms, in order to navigate. Now, first things first – Let’s see what a constellation is. Simplifying the definition given in the Wikipedia, I can say ” a constellation is a perceived pattern formed by prominent stars within apparent proximity to one another.” It must have been the bright sky without today’s light pollution coupled with the good imagination of the people from ancient civilizations that gave rise to these constellations. Many of the constellations were named after different animals or characters from mythological stories. I suspect some of them were defined by people who really had some extra time at hand as well , because only a few constellations resemble the figure they were meant to represent! Here is the constellation of Scorpius, where it is indeed easy to imagine a celestial scorpion is shown below.
The next important term that you need to understand is ecliptic. The ecliptic is the apparent path taken by the Sun on the celestial sphere. If this definition sounds like Greek or Latin, the diagram on the side should help! The celestial sphere is the imaginary sphere around us. If you project the earth’s equator on to the celestial sphere, you get the celestial equator. Since the Earth’s axis is not perpendicular to the plane it revolves around the Sun, the path of the Sun on the celestial sphere is also at an angle to the celestial equator. This path is called the ecliptic. But how to observe the path of the Sun among the stars since no stars are visible when the Sun is around? By observing the eastern sky just before sunrise, and the western sky just after sunset, it was possible for ancient civilizations to maps the path of the Sum among stars. The ancient civilizations who defined these constellations also observed that this path passed primarily through 12 constellations, which they called the Zodiac. Each of the constellation in the zodiac was assumed to occupy 30 degrees of longitude on the celestial sphere – the amount of distance covered by the Sun in the sky in one month’s time. Since the Moon, and other planets also revolve around the Sun in almost the same plane as the Earth, they are also always seen in the vicinity of the zodiac for Earth based observers.
There are two points in the sky where the ecliptic intersects the celestial equator. These are the days when equinoxes occur. One is the vernal equinox at the beginning of spring (so called vernal equinox), and the other beginning of the fall (autumnal equinox). About 1500 years ago, the spring equinox coincided with the beginning of the constellation of Aries, and the Sun was at this position around the 14th of April each year. Due to the phenomenon called precession, the vernal equinox is moving slowly on the ecliptic and now actually occurs around the 20th of March each year. However, western astrology still considers the vernal equinox as the ‘First point of Aries’ even though, the constellation of Aries may be far from it.
Until 20th century, constellation borders stayed sort of amorphous. In 1925, the International Astronomical Association defined constellation borders assigning specific boundaries between all the constellations in the sky, and dividing all the area of the sky into 88 constellations. When this new sky map was created, the ecliptic actually passed though 13 constellations instead of 12. The Sun actually moves through the constellation of Ophiuchus, between Scorpius and Sagittarius.
In the map here, you can see that the ecliptic passes through Ophiuchus before going to Sagittarius. But all this change happened about 85 years ago. But then why is it making big news now?
It is just that a fact that was known to astronomers and for others interested in the sky, was brought out as ‘news’ :) ! On January 15th 2011, when millions of people heard for the first time that the Sun goes through a 13th constellation, and when the exact times of the year during which the Sun is actually in a constellation were listed out by Minnesota Planetarium Society, hell broke lose for a lot of believers!
Now lets assess what is the impact of this on your life. There are two options for you. If you believe in western astrology, you can take the following stand to stop lot of heart ache – “According to western astrology, zodiac was divided the ecliptic into 12 equal parts. The first point of Aries has long since been disassociated with the constellation of Aries. So although I understand that the Sun was not even in the constellation of Leo when I was born, I am ready to believe I’ll have qualities of a Leo, because, well – astrology says so”. This is technically a correct argument. In summary, your sign did not change, based on the principles of astrology.
If you are a non-believer of astrology like I am, and don’t believe that the Sun or the Moon or any stars can predict your fortunes, then well and good! You don’t have to care a bit about any definition or redefinition of constellation boundaries. After reading this post, you can be happy about knowing one new fact about the sky, though ;)
Picture source : Normally I make it a point to give proper credit to pictures that I use in the blog posts. Unfortunately this time, I regret not saving that information, and not providing it in the post
p.s: This is a slightly modified version of the speech I gave today at my Toastmasters club. This was a project from the Advanced TM Manual – Speaking to Inform.
If you did not know, a nice planetary conjunction is coming up.
Watch the evening sky after the sunset for the next couple of weeks. Venus, and Jupiter, both very bright objects even from a light polluted sky are drawing closer.
On November 30/ December 1st, these two will be the closest. Don’t miss it – particularly so if you missed the conjunction of these planets early in the year in February 08.
Here is a simulation of the conjunction on YouTube.
And BTW, some people believe the “Star of Christmas” was indeed a very close planetary conjunction.
Today, July 09, 2008 – The big planet Jupiter is in opposition.
What does it mean?
Both the Earth, and Jupiter are on the same side of the Sun, and you can almost draw a straight line through them (Just for a moment assume all the three objects are in the same plane :) )
If you were able to go far far away above the solar system, you will see something like this.
I guess you’ll have to click on the picture to see anything :) The yellow dot is the Sun, the blue dot is the Earth and the green dot is the Jupiter.
You’ll see Jupiter for most part of the night. It rises around sunset, and sets around sunrise. Also, it is at its brightest, because it is at the nearest distance to Earth.
How to locate it?
Look in the Eastern/ South-Eastern sky about an hour after the sunset. You should see Jupiter as a brilliant white star. Glowing at magnitude of -2.7, there is no other star in the region which is as bright.
Here is a star map for those who are interested. Jupiter is in Sagittarius, just below the curvy Scorpious. Standing eastward, drop a straight line to the horizon from the bright red star Antares, and you will see Jupiter! Click on the image for a zoomed view.
These events are not rare events – Jupiter is in opposition once in about 400 days. But if you want to see Jupiter and it’s moons in a backyard telescope, this is probably the best time.