New solar telescope begins scientific observations

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The summit of Haleakalā pierces the sky at 10,000 feet above east Maui, and its name translates to "house of the sun." It makes sense, then, that one of the world's most popular places to watch the sun rise is the home to the Earth's largest, most powerful solar telescope.

Last week, the Daniel K. Inouye Solar Telescope (DKIST) conducted its first science observations, the latest milestone for a scientific instrument nearly three decades in the making.

An unparalleled stargazing spot

There is over a century of history of astronomy in Hawaii, and the stars have played a central role in ancient Polynesian and Hawaiian culture for millennia. Polynesians began exploring the Pacific Ocean 3,000 years ago, having mastered celestial navigation — using the stars to traverse vast distances.

In the late 1800s, King Kalakaua developed an interest in astronomy, and after visiting the Lick Observatory in California in 1881, was inspired to bring a telescope to Hawaii.

The islands are, objectively, a great location for stargazing. Low latitude, high altitudes (Haleakalā's height is second only to Mauna Loa on Hawaii Island, which is 13,600 feet high), relatively little light pollution, fairly stable atmospheric conditions above the clouds, clean air, and mild weather.

The proliferation of telescopes atop Hawaii's volcanoes, however, has been controversial, and protests over the construction of the planned Thirty Meter Telescope made headlines around the world in 2019.

The TMT project remains in limbo, and more emphasis is now being placed on removing telescopes rather than building them. But the Daniel K. Inouye Solar Telescope project has been proceeding carefully toward reality since the late 1990s.

Setting sights on sun seeing sites

The solar telescope was initially called the Advanced Technology Solar Telescope (ATST), an international project led by the U.S. National Solar Observatory (NSO).

After evaluating 70 potential sites, both national and international, Haleakalā was selected as the best location for the telescope in 2005.

"The ATST has been described as the world's greatest advance in ground-based solar telescope capabilities since Galileo," the announcement read.

While most headline-grabbing astronomy projects are aimed at the furthest reaches of the universe, this telescope's primary focus was very local.

"Few astrophysical research disciplines are directly relevant to life on Earth, but understanding and predicting the magnetic fluctuations of the sun is one that is," the announcement continued. "This variability touches Earth in several ways, principally through the sun's changing brightness, which affects the terrestrial climate both on the very long timescales that correspond with the rise and fall of civilizations and in periods as short as a few years."

(The site selection announcement, by the way, called for heeding native Hawaiian concerns, noting that "Haleakalā is a sacred place and must be treated with respect.")

The telescope specifications were ambitious, its 4-meter (13-foot) mirror able to collect seven times more sunlight than any other solar telescope, "capable of resolving a few tens of kilometers on the solar surface."

"The ATST design contains a large number of subsystems that push the limits of state-of-the-art technology," wrote NSO scientists in 2007, concluding that the instrument "will advance ground-based solar astronomy by a leap as big as those of Galileo and Hale."

The solar telescope project got a significant boost in with a $146 million federal grant to the National Science Foundation (NSF) under the American Recovery and Reinvestment Act of 2009, and a target completion date of 2015.

The NSF selected the NSO to manage the $298 million project the following year.

"ATST will be the largest and most capable solar telescope. No comparable facility exists or is planned," the NSO stated. "ATST will be the world's flagship facility for the study of magnetic phenomena in the solar atmosphere and will be the first large, ground-based, open-access solar telescope in the United States in more than 40 years."

In December 2013, as construction got underway, the ATST was renamed to the Daniel K. Inouye Solar Telescope in honor of Hawaii's late, influential senator.

First light and beyond

After years of construction, instrument installation, and testing, the solar telescope saw first light in December 2019, and the first images released to the public were spectacular.

What looks, at first glance, to be a square photo of a layer of hot corn kernels is in fact a 5,000-mile by 5,000-mile view of the surface of the sun, the highest resolution image ever captured.

"We can see features as small as 30km (18 miles) in size for the first time ever," the NSO declared. The turbulent, roiling gasses appear as cells or bubbles, each about the size of Texas.

The outer layers of the solar atmosphere is called the corona, and reaches temperatures of more than a million degrees.

Here's a video:

Six months later, scientists unveiled the first high-resolution image of a sun spot.

The image revealed striking details of the sunspot’s structure, sculpted by a convergence of magnetic fields and hot gasses. While sunspots are cooler than surrounding areas, they still reach temperatures of over 7,500 degrees Fahrenheit.

The imaged sunspot is relatively small, about 10,000 miles across — but still large enough to swallow the Earth.

A new era

The sunspot reveal was two long years ago. DKIST only commenced its first science observations on Feb. 23.

"The telescope’s operational phase is a long-awaited accomplishment, marking the end of a construction phase bookended by groundbreaking in 2012 and an 18-month delay caused by the COVID-19 global pandemic," the NSO explains.

Noting that solar activity can be disruptive to modern life — affecting power grids, communication networks, and other technologies — the DKIST is expected to represent a major tool in developing ways to predict space weather.

The start of scientific observations at DKIST also coincides with a new, 11-year solar cycle, which began with the lowest number of sunspots in December 2019. With "solar maximum" expected in mid-2025, last week's activation of the solar telescope is described as the dawn of a new era of sun observations.

Local politics notwithstanding, it is expected that the Inouye Solar Telescope will be operational for at least 44 years – or four solar cycles – through to the 2060s.

Header image by Ekrem Canli/Creative Commons.