The Pale Blue Dot

The Pale Blue Dot
Image: NASA

In 1990, after having completed its primary mission, Voyager 1 received instructions to turn its cameras back around to Earth. NASA had received a request from the famous astronomer Carl Sagan to photograph the Earth from 6 billion kilometers away, as the spacecraft was leaving the Solar System. In the resulting picture (above), Earth appeared to be just a tiny dot hanging in a beam of light in the middle of space, a "pale blue dot."

Carl Sagan's reflections about the picture are especially thought provoking and humbling. His words never fail to make me appreciate the value of humanity and our home planet.

From this distant vantage point, the Earth might not seem of particular interest. But for us, it's different. 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 "superstar," every "supreme leader," 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 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. 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.

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.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. 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. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

Carl Sagan later wrote The Pale Blue Dot: A Vision of the Human Future in Space*. Inspired by the photograph, Carl Sagan talked about the human future in space. Recently director Michael Marantz has constructed a wonderful short film based on an excerpt from the book. You can watch it below. (It looks great full screen in HD!)





Update: I found another great video on YouTube. This one is based on the based on the reflection written above.

*The book is available on Amazon, and is a great read. Please note that purchases made on Amazon.com through Amazon links on this blog help support this blog. A small portion of your purchase will automatically be donated towards this blog. You will not be charged extra for your purchase.

Rosetta Captures Stunning Picture of the Earth

ESA's Rosetta spacecraft, as it is conducting its final flyby of the Earth, captured a very stunning picture of the planet, showing an illuminated crescent. The image was made by combining images taken through the orange, green, and blue filters by the OSIRIS narrow-angle camera onboard. In the resulting picture, the South Pole and Antarctica are exposed in the sliver of the Earth illuminated.

As Rosetta approaches the Earth, space scientists will have an opportunity to study its orbital energy. Previous flybys of other crafts have shown mysterious variance in the amount of orbital energy, revealed as a small difference in the spacecraft's speed and the predicted speed. During Rosetta's flyby, its speed will be measured to see if there is a change.

Launched in 2004, Rosetta's mission is to study the comet 67P/Churyumov-Gerasimenko in 2014, as well as two asteroids. It will land the Philae lander on the comet. The lander will transmit data about the composition of the comet and will continue to study the comet as it approaches the Sun.

Image: ESA


Astronomy and Space Celebrates International Year of Astronomy 2009.

TMC Onboard Chandrayaan-1 Tested

The Terrain Mapping Camera (TMC) is among the numerous tools onboard Chandrayaan-1. Chandrayaan-1 is India's first Moon mission, and the TMC is designed to map the topography of the Moon. Using this camera, Chandrayaan-1 will be able to completely map the surface of the Moon. It was tested on October 29, 2008 by ISRO, and sent back wonderful images of our home planet, Earth. The instrument can take black and white images and has a resolution of 5 meters. The new images are posted below (click for larger view):

Images: ISRO

Hubble's 100,000th Orbit

The Hubble Space Telescope has just recently completed its 100,000th orbit around Earth today, August 11, 2008. The telescope reached that milestone above the Pacific Ocean (Illustration above). It has been a long journey for this famous telescope, 18 years long, one that has let humans learn so much about the universe. However, it has not always been an easy life for the Hubble, marked by quite a few challenges and repairs. To mark this special event, the researchers at the Space Telescope Institute in Baltimore, Maryland have decided to do something special.

These researchers decided to point the giant space telescope at a part of the nebula near star cluster NGC 2074. The nebula, 170,000 light-years away from us, is an intense area of star formation that may have been caused by a supernova explosion nearby. It is located in the Large Magellanic Cloud, which is a satellite of the Milky Way galaxy.

The colorful image taken by the Hubble, below, reveals many features of the nebula lighted up by strong ultraviolet radiation. Young stars existing in NGC 2074 are emitting strong radiation that is eating away the edges of the nebula. The area covered by the image spans a massive 100 light-years and huge towers of dust come out of the bright colorful walls of gas that form part of a large molecular cloud. To give a sense of scale, the seahorse-shaped tower at lower, right in the image measures about 20 light-years in length, approximately 4 times the distance between the Sun and Alpha Centauri, the nearest star to our sun!

This color image was taken by the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope on August 10, 2008. The Red colors show emission from sulfur atoms, green from glowing hydrogen, and blue from glowing oxygen.

Images: NASA

Leap Year

If you haven't looked at the calendar today, it's February 29, 2008. February 29 only occurs on leap years, and 2008 happens to be one. So what exactly is a leap year?

Basically, a leap year is a year containing one extra day. It supposedly is every year evenly divisible by 4, but it's more complex than that.

A tropical year, or solar year, is approxima

tely 6 hours more than 365 days. 6 hours is a quarter of a day, so one year is approximately 365.25 days long. Therefore adding one more day to the calendar every 4 years would make sense, making an average year 365.25 days long, and that's exactly what the Julian calendar does. But notice that a solar year is only approximately 6 hours more than 365 days; it's actually a bit shorter, about 365.24237

4 days long, and increasing. So to better approximate the length of the year, a better system was developed.

The Gregorian calendar is the most widely used one in the world. It was decreed by Pope Gregory XIII in 1582 to make sure Easter and the Vernal Equinox would fall at the same time. It modified the Julian calendar with a new rule. Leap years are years exactly divisible by 4, except years that are exactly divisible by 100, but centurial years exactly divisible by 400 are still leap years. What that means is that the 

year 1900 was not a leap year, but 2000 was. While in the Julian calendar, both 1900 and 2000 were leap years. The Gregorian calendar results in a better average year: 365.2425 days long, which gives a more accurate approximation.

Update: Google has made a Google Doodle for the Leap Year. It shows a frog "leaping" instead of the l in Google.