call for action

The future of stargazing is at risk because of a familiar, old enemy

"The smog prevents us from seeing the stars."


Astronomers spend quite a bit of time staring out into the sky, searching for stars and planets beyond our world. As they look up, they also become uniquely aware of what is happening on our own planet, too — and the outlook is not good.

The Earth's rising temperatures, record-breaking wildfires, and pollution are having an increasingly pernicious affect on astronomical observations.

Climate change influences the quality of observations obtained by astronomers around the world, and scientists from the field say they are concerned the ongoing crisis here on Earth may get in the way of their view of the cosmos.

The problem is becoming apparent in what some call the world capital of astronomy, Chile. Here, the desert provides exceptionally clear and dry viewing conditions for several observatories. But that is slowly starting to change.

At the Paranal Observatory of the European Southern Observatory in Chile, astronomers have noted an increase of the average temperature by 1.5 degrees Celsius over the past four decades. This rise is a problem for the telescopes on site, which need to cool during the nighttime to avoid malfunctions when the domes are opened at sunset.

The site for the Paranal Observatory in Chile has seen an increase in temperature, which would prevent the instrument from cooling down.


Faustine Cantalloube, a researcher at the Max Planck Institute for Astronomy, recorded the increase in temperature at the Chilean observatory to make the case against climate change herself.

"Seeing that for myself, seeing the temperature rise in my own data," Cantalloube tells Inverse. "I knew for years but seeing it for myself was very strange."

Astronomers typically pinpoint locations around the world that provide for good viewing conditions, a clear eye on the skies. This has proven more difficult in recent years, as they are no longer sure they can rely on the same places that they have used for decades.

Observatories are built on mountain tops where the weather is reliably good for around 300 days of the year, according to Travis Rector, a professor at the University of Alaska Anchorage's physics and astronomy department, and the chair of the sustainability committee at the American Astronomical Society.

"Over the next two decades, these observatories will see a change in the pattern of weather conditions," Rector tells Inverse. "We’re concerned about the longterm viability of these observatories."

In Chile, some locations are starting to have rain where it has rarely rained before.

Meanwhile, the ongoing wildfires in California threaten the prominent Mt. Wilson Observatory, which has been helping astronomers observe the universe for over 100 years. On Tuesday, the fires came within 500 feet of the observatory, which is located in the San Gabriel Mountains above Pasadena.

Earlier in August, firefighters saved the historic Lick Observatory from destruction by the fires in Northern California.

"The most immediate and dramatic example is the fires," Rector says. "Astronomical observatories are located on mountain tops in dry areas, and since climate change is making drought more severe and increasing fire risks, there is an increased number of fires near observatories."

Wildfires have destroyed observatories around the world before. In 2003, the fires in Australia swept through the observatory compound on top of Mount Stromlo.

Beyond the immediate weather conditions felt on Earth, an increase in wind shear in the upper troposphere, the lowest region of Earth's atmosphere, has resulted in a wind-driven halo that appears when the turbulence in the atmosphere varies faster than the telescope can correct for them.

The wind-driven halo limits astronomers' ability to view exoplanets.

"For now, a part of the wind-driven halo is more prominent and is preventing us from seeing exoplanets," Cantalloube says.

Pollution is another major concern for astronomers who have their eyes on the cosmos, but their view is being blocked by smog, aerosols, or light pollution.

Astronomers have already noted an increase in the amount of aerosols, which are small, light particles that essentially float in the atmosphere for a long time.

"[Aerosols] will decrease the amount of light that is able to make it down from space to our telescopes," Rector explains.

In Chile, Cantalloube has noted that the country's mining industry has led to an increase in the amount of aerosols in the atmosphere, as well as an increase in light pollution as the miners work through the night.

"Most observations can't be done without clear skies," Cantalloube says. "Some of the effects we see, probably due to aerosols, is that the smog prevents us from seeing the stars."

Looking ahead

Astronomers have started documenting these issues and calling for change — starting with themselves.

Knud Jahnke, a researcher at the Max Planck Institute for Astronomy in Germany, believes that the community should take responsibility for their own carbon emissions first.

"We always look into the skies, we’re one of the scientists that is quite aware of what’s going on in our atmosphere," Jahnke tells Inverse. "We own these emissions so we’re responsible."

Jahnke put together a carbon emissions assessment for his institute five years ago, and found that the biggest contributor was flights to and from conferences and observatories around the world. He and other astronomers agree on instituting more virtual conferences, and remote observations.

"Astronomers are responding in different ways, we know quite a bit on climate change because the science we do is connected to climate science," Rector says.

The physics of astronomy and climate science is largely the same. Astronomers who study the atmospheres of different planets like Venus and Mars also understand climate models here on Earth.

In fact, the planet Venus serves as an eerie look into Earth's future if we don't get greenhouse-gas emissions under control. Venus' atmosphere consists mostly of carbon dioxide and traps heat in the same way that greenhouse gases do here on Earth.

Astronomers also know that as far as life as we know it surviving in the vast universe, Earth is pretty much it for now.

"We have a unique perspective on the issue because we understand the finite nature of the Earth," Rector says. "Astronomers’ perspective is the Earth is it, this is the only place that we have a chance of all of us surviving so we have to be mindful of how we’re changing the climate."

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