Showing posts with label space. Show all posts
Showing posts with label space. Show all posts

Friday, 3 July 2015

Mini Blog: Shadows on Celestial Bodies, Umbras, and Umbrellas

I'm going to be starting a series called "Mini Blog", where each post in this series is significantly shorter than the lengthy posts I usually write. In fact, sometimes it may be just a picture. Like this one!


This picture defines umbra, penumbra, and antumbra.

Penumbra in this picture is B, and umbra is A.

The reason why the moon doesn't totally cover up the sun from our perspective on earth during a total eclipse is because the distance between the moon and the earth is around the same distance where the apex of the moon's umbra because of the sun is. Therefore, we see an antumbra instead of a full umbra.

Another fun fact: umbra is the Latin word for shadow. The English word, "umbrella", is also derived from the Latin word "umbra".


Friday, 23 September 2011

Earth and I

Our Pale Blue Planet


"We only inhabit one of the eight planets around an insignificant sun, and on this planet, Earth, rests over 1.7 million species. You are right - we are specks, among specks, among “billions and billions of specks” on the cosmic scale. However, Earth is significant to us, and we are significant to family and loved ones; for me, that is all that I need to feel significant."

Monday, 4 April 2011

The Pale Blue Dot - Carl Sagan





Consider again that dot. That’s here. That’s home. That’s us. On it, everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘supreme leader,’ every ‘superstar,’ every saint and sinner in the history of our species lived there — on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. Like it or not, for the moment, the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. It underscores our responsibility to deal more kindly with one another, and to preserve and cherish the only home we’ve ever known, the pale blue dot