Dr. John P. Holdren, The White House

I'm the President's Chief Science Advisor. And from time to time, I like to send quick, ad-hoc notes to White House staff on a variety of topics -- upcoming lunar eclipses, groundbreaking climate news, incredible photos from space. Things I've come across and found fascinating.

Apparently, people really like them. So when a colleague recently suggested I start sending these notes a little more widely, I figured I'd give it a try.

Here's what I passed along internally Monday morning:

Today's morning report from NASA contains a Hubble photo I thought worth sharing. The astonishing density of stars -- most of which, we now know, have planets -- really does make one wonder whether there's anybody else out there. And this is just one piece of our own galaxy. There are an estimated 100 billion other galaxies in the observable universe. Enjoy!

Is there a particular scientific topic you're interested in, or a question you have? Let me know here.

Even if I don't know the answer, we've got a lot of smart people over here who might.

My best,

John

Dr. John P. Holdren
Director, Office of Science and Technology Policy
The White House
@whitehouseostp

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Hubble Peers into the Most Crowded Place in the Milky Way

This NASA/ESA Hubble Space Telescope image presents the Arches Cluster, the densest known star cluster in the Milky Way. It is located about 25,000 light-years from Earth in the constellation of Sagittarius (The Archer), close to the heart of our galaxy, the Milky Way. It is, like its neighbor the Quintuplet Cluster, a fairly young astronomical object at between two and four million years old. The Arches cluster is so dense that in a region with a radius equal to the distance between the sun and its nearest star there would be over 100,000 stars! At least 150 stars within the cluster are among the brightest ever discovered in the Milky Way.

These stars are so bright and massive that they will burn their fuel within a short time (on a cosmological scale that means just a few million years). Then they will die in spectacular supernova explosions. Due to the short lifetime of the stars in the cluster the gas between the stars contains an unusually high amount of heavier elements, which were produced by earlier generations of stars.

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