The Science Seat: Sun will fry Earth – ‘Sorry!’

Posted at 8:32 AM, Feb 11, 2013
and last updated 2013-02-11 10:41:20-05

Astronomer Jason KaliraiBy Nana Karikari-apau, CNN

(CNN) — Editor’s note: The Science Seat is a feature in which CNN Light Years sits down with movers and shakers from many different areas of scientific exploration. This is the first installment.

Jason Kalirai is the deputy project scientist for the James Webb Space Telescope, which will be NASA’s next big mission in astrophysics. He works at the Space Telescope Science Institute in Baltimore.

Last month, Kalirai, 34, won the American Astronomical Society’s Newton Lacy Pierce Prize for his achievements in observational astronomy. CNN Light Years recently spoke with him about his work. Below is an edited transcript.

CNN: What inspired you to pursue a degree in science?

Jason Kalirai: As far back as I can remember, I was curious about the way things work. I’m sure I got this trait from my father, whom my friends actually nicknamed “MacGyver” when we were growing up. He enjoyed questioning how things operate and then trying to solve everyday problems through experimentation.

When I was in elementary school, I was fascinated by the night sky, and I wanted to understand the scale of the universe — how big it was, how separated the stars were, what else was out there? I started reading books about the Milky Way galaxy and the universe, put posters of our solar neighborhood in my room and kept asking the question “why.” Science not only provided me with the answers to these grand questions, but it opened up new mysteries that I was motivated to learn about.

CNN: What are five steps through which an astronomer solves a problem?

Kalirai: Astronomical research has many components to it. Astronomers are well-rounded and excel at problem-solving, data acquisition and analysis, writing reports and presenting results. Solving a single problem can take many years through this cycle:

In the first step of the process, astronomers design an experiment to solve a particular problem that they are interested in. Usually, this involves writing a proposal to use a telescope to gain new insights on the universe.

Next, astronomers obtain the observations. For ground-based astronomy, this typically means traveling to a mountaintop and collecting data, whereas for space-based observations the data are sent directly to the astronomer.

Scientists then analyze the observations using powerful computers, usually in their own offices. They also spend time writing computer programs to aid in the analysis. New discoveries are rare, so it takes very careful attention to details in the data.

Astronomers publish (their) results in peer-reviewed journals, so they have to write detailed reports of all of their findings. These reports are judged by other astronomers to make sure they are based on sound principles.

Finally, astronomers present their findings to the science community through domestic and international meetings.

CNN: What kind of astronomer do you consider yourself?

Kalirai: My focus is on observational astronomy, and I’m particularly passionate about using telescopes to push beyond the limits of what we’ve already seen. I try to discover new population of stars in our Milky Way galaxy and try to reveal new parts of galaxies in the nearby universe. Whenever I can get access to a new capability or technology in astronomy (e.g., a more sensitive camera), I like to take that tool and apply it to the kind of science problems that I most enjoy working on.

CNN: Why do you focus on star clusters?

Kalirai: Star clusters are one of the universe’s most remarkable environments. In a small region of space that is not too much larger than the distance between the sun and the nearest few stars to the sun, a cluster contains thousands of stars. These stars share incredible similarities, all having formed at the same time millions of years ago and with the same chemistry. The only difference between the individual stars is their mass, and mass happens to be the primary factor that controls how stars evolve (e.g., how long they live for, how bright they become and how they die).

So, observations of each individual star cluster give us a snapshot of how stellar evolution has shaped a population with that age, and we can complete a picture of stellar evolution by observing many clusters with different ages. As a result, star clusters anchor much of our knowledge of the universe.

CNN: How exactly do stars evolve over time?

Kalirai: We are used to thinking of the stars as fixed points in the night sky, but they actually go through a life cycle, just like humans. Newborn stars are very active and energetic, kind of like my twins. Stars in their middle years are kind of boring (dare I say, like our parents), and can spend billions of years not doing much other than converting hydrogen into helium. Toward the end of their lives, stars become “cool” again, kind of like grandparents are “cool.” The lifetimes of stars are so much longer than human lifetimes that we see them as being fixed over generations. But they all evolve from stellar birth to stellar death.

CNN: What is the main goal of your research program?

Kalirai: The main goal of my research is to understand the details of how stars like our sun, including those that are a little more and a little less massive, change over time. For billions of years, these stars will remain at the same brightness and temperature. This is great for humans on Earth since it gives us a stable climate. After the hydrogen in the sun is exhausted, the sun will become a stellar cinder and simply cool over time. We call this state, the end state of 98% of all stars, white dwarfs.

All of the action in stellar evolution occurs between these two phases, when, over a relatively short time scale, stars swell up into “giants” and spill their outer materials into space. The detailed understanding of this process, of how stars dramatically change, is fundamentally important to many research areas in astronomy. After all, the light that we see from distant galaxies is really just millions of individual stars at the tip of their luminous evolution.

CNN: If the sun will experience this dramatic change, what is the fate of our planet Earth?

Kalirai: The Earth is orbiting the sun at a distance of about 90 million miles. When the sun runs out of hydrogen in its core, it will begin burning hydrogen in a shell around the core and become very luminous and bloated. The outer layers of the sun will actually reach the Earth, and so the oceans will evaporate and our planet will be fried. Sorry! Fortunately for us, this won’t happen for several billions of years.

Based on my research on “stellar mass loss,” the sun itself will lose about 45% of its mass through this process. The remaining mass, the core of the sun, will be the white dwarf. Interestingly, the size of that core will only be a little larger than the Earth, so the remnant star will be very dense.

CNN: What telescopes do you use to study the stars?

Kalirai: I enjoy using the Keck telescopes on Mauna Kea in Hawaii. Over the past seven years, I’ve traveled to Hawaii to collect data from these telescopes more than a dozen times. The Keck telescopes are two of the biggest optical telescopes we have on Earth. The mirrors stretch over 30 feet across and the building itself is bigger than a house.

The site of the telescopes is also beautiful. Mauna Kea is a dormant volcano, and the telescopes sit at the peak, at the distance of 13,000 feet. It’s a harsh environment to observe from since there is about 40% less oxygen at that altitude than sea level.

CNN: You recently received an award from the American Astronomical Society called the 2013 Newton Lacy Pierce Prize. What does it mean to your career, and how does it affect your future endeavors?

Kalirai: The Pierce Prize is the biggest honor that I’ve received in my life. I am very passionate about astronomy and work very hard, so receiving the Pierce Prize tells me that the rest of the astronomy community values my contributions. This means a lot to me and will motivate me to work even harder in the future.

CNN: What do you see as the major achievement of the Hubble Space Telescope so far and its most important discoveries?

Kalirai: Actually, I think its best years are ahead of it. It’s amazing when a scientific tool can rewrite a textbook, but Hubble has managed to do it countless times. In 2009, astronauts serviced Hubble and put two new cameras on the telescope. These instruments are functioning fantastically, and the demand for Hubble observations by the astronomical community is the highest that it’s ever been. I have absolutely no doubt that Hubble will continue to amaze us with new discoveries about the universe.

CNN: You also spend a significant part of your time working on the James Webb Space Telescope, the successor to Hubble. Tell us about this fascinating project?

Kalirai: The James Webb Space Telescope is one of the most ambitious scientific projects that humans have ever undertaken. NASA has partnered up with the European and Canadian space agencies to build an unprecedented telescope, one that is the size of a tennis court and will launch 1 million miles away from Earth. (Hubble orbits at 350 miles.)

Webb, as we call it, will be 100 times more powerful than any other telescope we’ve made, and is designed to revolutionize our understanding of the universe. It will seek the first stars and galaxies that formed in the universe, solve mysteries on how stars and planets form and look for water in the atmosphere of other worlds. I can’t wait to use it.

CNN: What are the most rewarding things about being a scientist?

Kalirai: Professionally, it’s the fact that there is continuous satisfaction in expanding our knowledge of the universe. There are countless mysteries about the universe that we presently don’t understand, and it’s amazing to be a part of the process that will yield answers to these questions.

Personally, it’s very rewarding to see young people becoming curious about the way things work. I spend one day every month doing public outreach, where I visit science centers, planetariums, classrooms and other venues to communicate science. As I get kids excited about the STEM fields (science, technology, engineering and mathematics), I always try to leave a little nugget of information untold. It’s extremely rewarding to get the phone call or e-mail afterward when you realize that you’ve sparked their interest in science.

To see what scientific thoughts are on Kalirai’s mind today, you can follow him on Twitter at @JasonKalirai. Information about his research is also available on his Web page,

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