Our Home World, As Seen from Interplanetary Space

Friday and Saturday people around the world stepped outside and smiled waved to the sky. With that innocent action, they signified that WE are here on this planet. Across the solar system, spacecraft at Mercury and Saturn captured the moment.  Cassini at Saturn and MESSENGER at Mercury documented our planet from their unique vantage points in space.

The first images from that interplanetary photo shoot are now on Earth, being studied by scientists. They’ve made them available for us to see.

That’s our home, folks. It’s where we live. It’s all we got.

I’m going to leave you with the words of the late Carl Sagan, the scientist who inspired ME to get into science communication. He wrote in his book Pale Blue Dot, “From this distant vantage point, the Earth might not seem of any 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…

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.”

Think about his words. What do they say to you?

The Iconic Ring Nebula in a Different Light

Earlier this summer the folks at the Hubble Space Telescope Science Institute released a gorgeous multi-wavelength view of the Ring Nebula.  It’s a summertime sight for those of us in the northern hemisphere and a wintertime sky object for those in the southern hemisphere who live far enough north to see it. You need a telescope to spot it, and to really see the great details of this expanding cloud of gas and dust, you need the combined power of the Hubble Space Telescope along with several ground-based telescopes, and infrared data from the Large Binocular Telescope in Arizona.

What they show us is not just the iconic Ring Nebula we’ve all come to know and love, but they also give us an infrared peek at the space around the nebula. This is a planetary nebula —the last gasp of a sun-like star as it dies. Hidden from optical view but clearly apparent in infrared light are scallop-shaped bands of material that were actually blown away from the central star earlier in its evolutionary path toward forming the nebula.

The blue-colored gas in the central area of the  is actually a football-shaped structure that pierce into a surrounding cloud of reddish-colored doughnut-shaped material. If you click on the image at left you’ll get a much larger version that you can explore and spy out dark, irregular knots of dense gas embedded along the inner rim of the ring. The knots look like spokes in a bicycle.

Someday our Sun could look something like this as it takes the pathway toward planetary nebula-hood and eventual old age as a white dwarf. Once it uses up all the hydrogen in its core (in about 5 billion years), the Sun will star to expand and become a bloated red giant. Then, it will expel all its outer layers, leaving behind a very hot, very small and dense white dwarf. It will take billions of years to cool down and become a darkened cinder of a once-bright star. If you look closely at the enlargement of the Ring Nebula, you’ll see its little white dwarf. It could live as long as 15 or 20 billion years!

I find planetary nebulae very intriguing. They are at once spooky and gorgeous, and they tell a story of star life that we’ve only recently come to comprehend. There are still many details of the story for astronomers to learn. Knowing how our star will come to its end helps them understand the endless cycles of star birth and death in the cosmos.