Monday, July 27, 2015

Some Thoughts on the Discovery of Earth’s Bigger, Older Cousin

by Salman Hameed


An artist conception of Kepler 452b (Credits: NASA Ames/JPL-Caltech/T. Pyle)

Hold the celebrations: We will find an even better one soon!

While we wait, here are some thoughts on the newly discovered older, bigger, (badder?), cousin of Earth (you can also listen to my conversation with Monte Belmonte for our local radio station, WRSI, here):

The light from the star Kepler 452 dimmed just a fraction. Then, 385 days later, it did it again. Astronomers now know that a planet - only a little bigger than the Earth - is causing the dimming as it blocks some of the light heading our way. It is orbiting a sun-like star and is the closest analog to Earth discovered yet.

This way of detecting planets is called “Transit Method” and it has turned out to be one of the most successful ways of identifying other worlds. So far astronomers have detected 5583 planetary candidates around stars other than our Sun, with 1879 already confirmed (you can track the latest number of planets from Planet Quest.

Wait. Take a deep breath. Now imagine almost 1900 confirmed planets outside our solar system! To put this in perspective, though the entire history of humanity, save the last two decades, we knew of planets only in our own solar system (we even managed to demote one of them!). It was only in 1995, that astronomers confirmed the existence of the first extrasolar planet – 51 Peg and the number of planets is now steadily increasing.

Most of the planets discovered so far are much bigger than the Earth and often lie quite close to their parent star (much of this is a selection boas as detection techniques are better in detecting these kinds of planetary systems). But, of course, we want to find Earth-like planets – small, rocky worlds, orbiting sun-like stars at a distance where water can exist in liquid form. This last bit is potentially important for life. Neither too hot, nor too cold. This is called the Goldilocks zone or more formally, the Habitable Zone. In our own solar system, Venus is too close to the Sun and Mars just a little too far. But Earth is in the middle of the habitable zone and has ably supported life for the past four billions years!

If we can find earth-sized planets in their respective habitable zones, the thinking goes, then these may be the likely places where life may have also originated. And on at least some of these worlds, biological evolution would have led to the development of complex organisms as well.

But wait. One step at a time. First we have to detect earth-sized planets in habitable zones. In 2011, astronomers discovered an earth-sized planet, Kepler 20e. But its orbit was only 6-days long and therefore too close to the Sun. The same year came the discovery of Kepler 22b. This time the planet was in the habitable zone of a sun-like star, but it was double the size of the Earth and it is quite likely that it is made of predominantly gases (like Jupiter and other big planets of our own solar system). Then in April of last year, astronomers discovered Kepler 186f. It is an Earth-sized planet in the habitable zone. It is a promising candidate but with just one potential catch. It orbits a star that is smaller and dimmer than our Sun. Its habitable zone, therefore, is closer to its star. I think this is a great candidate for a planet that might host life. The only thing is that it does not orbit a sun-like star.


That brings us to Kepler 452b. This planet is 60% bigger than the Earth. It orbits a sun-like star and it takes 385 days to go around its star. Astronomers think that it has an atmosphere thicker than the Earth and that it also has active volcanism on its surface. So far so good. However, it is located 1400 light years away. Even if we were to find a way to travel fast, this will still be a little too far away. In addition, the planet is 1.5 billion years older than the Earth. This can be both good and bad. This older age gives the planet plenty of time for life to develop. On Earth, life started early, but then it took several billion years to develop complex species like the Turtles, the elephants, and the species that are looking for life on other planets. Just because it happened this way on Earth is no guarantee that it will happen the same way on another planet. But having more time – 1.5 billion more years – nevertheless is probably good when it comes to possible diversity of life.

On the other hand, the central star of Kepler 452b is also 1.5 billion years older, and it means that it is also a bit brighter than our Sun. Stars like our Sun brighten up a little as they age and that can have potentially devastating impact on the habitability of planets. Our own Sun will get 10% brighter in the next billion years or so, and this extra heat will probably result in the evaporation of oceans on Earth making our planet inhospitable to life as it exists today. It is impossible to predict the future of humanity – or whatever our future descendants will be called – that far into the future. Nevertheless, relocation will be the only option for survival, if they still reside on our planet. But we don’t know for sure if the slightly larger size and being slightly farther away from the sun will give Kepler 452b some extra time for habitability or not.

Kepler 452b is a great candidate for life. But hold the celebrations. Astronomers estimate that 10% of stars in our galaxy host Earth-sized planets that may exist in the habitable zone. In a galaxy of 200 billion stars, that leaves us with 20 billion potentially habitable planets! I am quite sure – no, I am certain that within the next few years, we will find even more promising candidates much closer to home. And I am quite sure that on at least one of these worlds, we will detect an atmosphere that has been transformed by the existence of life on that planet.

Now that will be something worth celebrating. Stay tuned. 

Sunday, July 26, 2015

A new episode of "Hamari Kainaat" on evolution of stars and HR Diagram

by Salman Hameed


Here is our latest episode of Hamari Kainaat (Our Universe) on evolution of stars. In particular, we spend time discussing the Hertzsprung-Russell (HR) diagram. It is a tool of understanding how stars function and evolve over their lifetime. We are still not done with HR diagram. I think we have at least two more episodes in the future dealing with it. In the mean time, here is an introduction on this in Urdu. For more episodes, please visit the website of Hamari Kainaat.


"Hamarai Kainaat" (Our Universe) is an Urdu Podcast about Astronomy, published by Umair Asim and Dr Salman Hameed. One of our main purpose for this podcast in Urdu, is to share the knowledge about our Universe to anyone relating to any walk of life in Pakistan and beyond.

Saturday, July 18, 2015

A Saudi supercomputer joins the list of most powerful computers

by Salman Hameed

I have posted about King Abdullah University of Science and Technology (KAUST) mostly from a skeptical lens (for example see Coed Saudi University for Saudi Elites?). It is a rich university (the second biggest university endowment in the world!) and that lends to the perception that it is buying its prestige. Plus, the campus is shielded from some of the more abhorrent Saudi laws (for example, the prohibition of women from driving - still!!) and appears to be catering either to the elites or to researchers from abroad. Nevertheless, KAUST is now starting to make some headlines and we should give credit where credit is due. Here is a blurb about Saudi Arabia from Nature's analysis of publication of articles in top journals:
Strong research output requires more than big investments. Saudi Arabia has poured billions into new universities, particularly with the 2009 opening of King Abdullah University of Science and Technology (KAUST), which is believed to have a US$15 billion endowment, and has attracted top talent for research. From 2012 KAUST has increased its article output in the Nature Index by 40%. Given its more moderate increase in WFC over the same time period, it seems that KAUST researchers are actively contributing more to collaborative papers than working in isolation. 
Performance in the Nature Index is also greatly dependent on collaboration — and this is where the Arab states are doing well. Saudi Arabia reaches out extensively to other countries for scientific collaboration, with 79% of its output being the result of international collaborations. Israel and Turkey collaborated internationally on 46% and 59% of their papers, respectively, showing that scientists in Saudi Arabia collaborate much more than their colleagues in neighbouring countries. This high collaboration rate, however, may be due in part to the practice at some universities — although not KAUST, which opposes such an approach — of bringing in foreign researchers for a short amount of time to add a local affiliation to papers.
In case you are wondering, here is how the region looks like (I will have more on Iran and Turkey separately):


This is how Fractional Weighted Count (WFC) and Nature Index is described:
The Nature Index is a unique database that tracks affiliations in research publications in a select group of scientific journals. The Index can provide an indicator of high-quality research contributions from institutions, countries, regions and disciplines. In this Global Nature Index supplement, we present a snapshot of the Index for the calendar year 2014. 
We have grouped countries into nine regions. The strongest performances come, not surprisingly, from North America, North & West Europe, and East & Southeast Asia. In fact, these three regions accounted for 91% of the Index's weighted fractional count (WFC), a metric that apportions credit for each article according to the affiliations of the contributing authors.
It is good to see that KAUST has substantially improved its article output. And now there is also news that a KAUST supercomputer has joined in the list of top 10 most powerful supercomputers (tip from Vika Gardener):
For the first time, a system in the Middle East earned a Top 10 spot on the Top500.org list of most powerful supercomputers. Shaheen II, located at King Abdullah University of Science and Technology (KAUST), in Saudi Arabia, placed 7th in the the semi-annual competition, the results of which were announced earlier today. Shaheen II is a Cray XC40 system that cranked out 5.536 petaflops per second on the Linpack benchmark. 
Shaheen II replaced the Shaheen I in April 2015. The 16-rack IBM Blue Gene/P supercomputer system and has 6,100 sets of 32 processor cores. At KAUST, 25 percent on the university’s faculty, students and researchers rely on Shaheen II, the university said in a press release. The system is used for and small- and large-scale scientific research, including global climate projects and visualizations of the brain and DNA.
In case you are wondering, Chinese supercomputer is the most powerful in the world:
At the top of the list, China and U.S. battled it out for the number one position. But, Tianhe-2 did it again. The supercomputer developed by the National University of Defense Technology in Guangzhou, China, held its number one title for the fifth consecutive time. No other supercomputer was able to beat Tianhe-2’s max calculation capacity of 33.86 petaflops per second. The top supercomputer in the United States, Oak Ridge National Laboratory’s Titan, remained at its number two spot achieving 17.59 petaflops per second.    
"Made in China" is now getting a new meaning! Read the full article here (you will need subscription for the full article). 

Tuesday, July 14, 2015

Time for Pluto has come...

by Salman Hameed

I have been behind on writing here (there are many many backlogged posts). But I had to say something about Pluto. So couple of things: First, here is an excellent video from Slate that shows the evolution of images of Pluto since 1930 (yes - not much until this month):

Then also see this video from NYT from last week:

And then finally, see this image of Pluto taken on July 12th: 

Pluto appearing as a world. This picture was taken by the New Horizons spacecraft on July 12th, when the spacecraft was still 2.5 million kilometers away. On July 14th, it will see Pluto from mere 12,500 kms away. Image credit NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute

And here are some thoughts on this encounter with Pluto:

Pluto: Smile - we are ready to snap your picture!

If you are out and about in the morning of July 14th or you are sitting at home reading this article. At 7:49am Eastern Daylight Time, symbolically look up at the sky (please don’t stare at the Sun). At this precise moment, a machine built by humans will be making its closest approach to Pluto – at the frontiers of our Solar system. This spacecraft, New Horizons, has been traveling at the incredible speed of 50,000 km/hour (if you are not impressed, check your speedometer when you are driving on a highway and compare with this Pluto probe)! And yet, it has taken nine long years to get to Pluto. Don’t blame the spacecraft. Pluto is currently 5 billion kilometers away and even one of fastest spacecrafts ever built by humans has taken this long to get there.

An American astronomer, Clyde Tombaugh, discovered Pluto in 1930. For the past 85 years, Pluto was seen as a small fuzzy object. Even the best telescopes could not make out much detail. In fact, four of its five moons have been discovered in the last ten years. In the last few days, however, Pluto has become a real world. Look at the photograph above. This is our best image of Pluto yet. It was taken on July 12th, when the New Horizons spacecraft was 2.5 million kilometers from Pluto. We can already see a couple of craters on the surface, as well as some cliffs (see the annotated image below).


But hold your breath. The spacecraft will take pictures of Pluto from a distance of only 12,500 kilometers – its closest approach. What kind of secrets will Pluto reveal then? Will there be ice volcanoes? Or evidence of sub-surface ocean? Or perhaps the spacecraft will find things that we have not even imagined about this cousin of ours living in the outskirts of the Solar system? Whatever it will be, it will be different and stunning. This is the lesson we have learned from explorations of eight planets and their moons.

Until recently, Pluto was the ninth planet of our Solar system. However, in a contentious decision, its status was demoted to a dwarf planet in 2006. I have my own bias in keeping its status as a planet. I obtained by doctorate from the astronomy department at New Mexico State University in the US. Clyde Tombaugh founded this department, and I had a chance to meet him and to be present at his 90th birthday in 1996. He died the next year, but Pluto retained a special place for astronomers in our department. With the renewed interest in Pluto, I hope its status will be restored as a planet.

Once New Horizons flys past Pluto, it will take a picture of Pluto in the shadow of the Sun. An eclipse. This will happen at 8:51am Eastern Time. The goal of the image is get information about the atmosphere of Pluto. But this picture will also tell us that this machine built by humans, has successfully gone past one of nine major bodies in the Solar system.

So today, at 7:49am (EDT), take a deep breath. Then look up in the sky and appreciate what humans can do at their best.

You can follow the latest about the Pluto encounter at http://pluto.jhuapl.edu/index.php