APOD 4.8

 

The hour-glass figure of this planetary nebula is ironic -considering how brief this stage in the star's life will last. With the nuclear fuel exhausted, the star is ejecting its outer layers as its core cools to a white dwarf. The "red" of the gas is digitally created to represent nitrogen, the "green" is hydrogen, and the "blue" is oxygen. The clear imaging of the nebula ejection process is helping to solve mysteries of the complexity of planetary nebulas.

APOD 4.7

 

It's strange to think that when you die, the world will go on without you. Science and technology will keep innovating -maybe even to the extent that could have saved your life if it was invented earlier or you were born later. Either way, our current 2015 North Star is Polaris, however, if you were born much later, say, around 14000, your North Star would be Vega. The picture above is how an exposure picture taken in the same place will change on its own. Once a few generations die, Vega will be the "norm" for a North Star -but if you're reading this, there's a good chance you won't live to see that. The shift is caused by the Earth's axis of rotation precession period of about 26,000 years - of which it has been 14,000.

APOD 4.6

I think at one point in our childhoods, when we were all asked "What do you want to be when you grow up?", and all of us answered "An astronaut!". And this picture can do a fine job to answer the follow up question, "Well, why do you want to be an astronaut?". That little speck on the dark side of the picture is the International Space Station -where astronauts can survive for periods of time in space. The ISS gets a nice view of sights skewed by our atmosphere -as well as the ability to look down on Earth. Tools are available on-line to let you know when the ISS will be visible from your location.