Hesman studies Neptune for key to solar system’s origin
By Elizabeth Frogley
Brigette Hesman wants to know how our solar system was created.
Hesman, a PhD student in astronomy, is studying Neptune to find out what the planet is made of. Knowing this will help astronomers figure out how Neptune – and all of our solar system – was formed.
“A lot of astronomy is bigger and better. I want to look at what’s on our doorstep first,” Hesman says. “In my lifetime we have the ability to send spacecraft to Neptune and know for sure what it’s like – to prove theories and confirm observations.”
Neptune, like Jupiter, Saturn and Uranus, is gaseous – it doesn’t have a surface you could stand on, but is made up of a dense cloud of gases held together by the planet’s spin. Neptune is mostly hydrogen and helium, but it’s the small amount of carbon monoxide in the outer atmosphere that Hesman is interested in.
If carbon monoxide is only present in the outer atmosphere, it likely came from an external source. But, if it’s present deep inside the planet, it must have been produced by a heat source at the planet’s core.
Astronomers currently don’t know if Neptune has an internal heat source, but they have to find out in order to develop theories about how the planet was formed.
“The big thing in astronomy is trying to find another Earth – a planet that could support life. But we have to know what we’re looking for before we’ll have a chance of finding it,” Hesman says. There are millions of solar systems out there, so astronomers have to know the conditions that created ours before they’ll have any chance of finding one like it.
When our solar system began, all of its elements were part of a nebula – a swirling mass of matter from which the sun formed. As the sun began to form, the elements not needed were expelled. The lightest elements, like helium, were flung the farthest from the sun, while heavier things like the rocks of earth remained closer to the sun.
Scientists used to think all solar systems were structured like ours, with small, rocky planets like Earth near the sun and large, gaseous planets farther away. The discovery of solar systems where large, gaseous planets orbit close to the sun has shown it’s not that simple. Astronomers need to know more about our solar system and the conditions that led to life forming on Earth.
“What are the conditions to produce an Earth? Well, we have one here so we need to find the conditions that formed it,” Hesman says.
Hesman studies Neptune from an observatory on Mauna Kea in Hawaii. Mauna Kea is an ideal location for astronomy because it is 14,000 ft. above sea level, where water in the atmosphere doesn’t distort the view and most of the clouds lie below the observatories. As well, Hawaii is isolated enough that the effects of light pollution are eliminated.
Hesman adds that because Mauna Kea is such an ideal location for astronomy, there’s tough competition for research time. To get access to the observatory for two or three days, Hesman must submit a proposal nearly a year in advance, detailing the research she plans to do.
Hesman’s research is significant enough that she’s been granted research time there in the past, and she is optimistic that she’ll be able to continue to study Neptune from the top of Mauna Kea.
“Everyone wants to find life on other planets, but before that we have to find life on our planet – we have to look internally to see how our system was formed,” she says.