The Sun burns 5 million tons of hydrogen fuel per second
LAST WEEK, on January 29, 2020, the first images released from the National Science Foundation’s (NSF) Daniel K. Inouye Solar Telescope reveal unprecedented detail of the Sun’s surface and preview the world-class products to come from this greatest 4-meter solar telescope. NSF’s Inouye Solar Telescope, near the summit of Haleakala, Maui, in Hawaii, will enable a new era of solar science and a leap forward in understanding the Sun and its impacts on our planet.
NSF’s new ground-based Inouye Solar Telescope will work with space-based solar observation tools such as NASA’s Parker Solar Probe (currently in orbit around the Sun) and the European Space Agency/NASA Solar Orbiter (soon to be launched). The three solar observation initiatives will expand the frontiers of solar research and improve scientists’ ability to predict space weather.
Space weather or activity on the Sun can affect systems on Earth. Magnetic eruptions on the Sun can impact air travel, disrupt satellite communications and bring down power grids, causing long-lasting blackouts and disabling technologies such as GPS.
To observe the Sun in unprecedented detail, the telescope features a huge mirror — the largest ever for a solar telescope. The surrounding observatory sits around 10,000 feet (3,048 metres) above sea level at the mountain’s summit, offering astronomers unparalleled viewing conditions.
To protect Inouye from the enormous heat generated by focusing around 13 kilowatts of solar power, the telescope has a specialised cooling system that includes more than seven miles (11.3 kilometres) of piping.
Close-up view of the Sun’s surface
The first images from NSF’s Inouye Solar Telescope show a close-up view of the Sun’s surface, which can provide important detail for scientists. The images show a pattern of turbulent “boiling” plasma that covers the entire Sun. The cell-like structures — each about the size of Texas — are the signature of violent motions that transport heat from the inside of the Sun to its surface. That hot solar plasma rises in the bright centers of “cells,” cools off and then sinks below the surface in dark lanes in a process known as convection.
CATEGORIES OF SOLAR STORMS
The National Oceanic and Atmospheric Administration’s (NOAA) uses its space weather scales to categorise solar storms.
They were introduced as a way to communicate to the general public the current and future space weather conditions and their possible effects on people and systems.
The scales describe the environmental disturbances for three event types: geomagnetic storms, solar radiation storms, and radio blackouts.
The scales have numbered levels, analogous to hurricanes, tornadoes, and earthquakes that convey severity.
G5 – Extreme
Power systems: Widespread voltage control problems and protective system problems can occur. Some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
Spacecraft operations: May experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.
Other systems: Pipeline currents can reach hundreds of amps, high frequency radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic latitude).
G4 – Severe
Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic latitude).
G3 – Strong
Power systems: Voltage corrections may be required, false alarms triggered on some protection devices.
Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50°geomagnetic latitude).
G2 – Moderate
Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions.
Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55° geomagnetic latitude).
G1 – Minor
Power systems: Weak power grid fluctuations can occur.
Spacecraft operations: Minor impact on satellite operations possible.
Other systems: Migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).
To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF’s National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 13-foot (4-meter) mirror — the world’s largest for a solar telescope — with unparalleled viewing conditions at the 10,000-foot Haleakala summit.
Focusing 13 kilowatts of solar power generates enormous amounts of heat — heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.
The dome enclosing the telescope is covered by thin cooling plates that stabilize the temperature around the telescope, helped by shutters within the dome that provide shade and air circulation. The “heat-stop” —a high-tech, liquid-cooled metal donut) blocks most of the sunlight’s energy from the main mirror— allowing scientists to study specific regions of the Sun with unparalleled clarity.
The telescope also uses high-tech adaptive optics to compensate for blurring created by Earth’s atmosphere. The design of the optics reduces bright, scattered light for better viewing and is complemented by a cutting-edge system to precisely focus the telescope and eliminate distortions created by the Earth’s atmosphere. This system is the most advanced solar application to date.
Physics behind space weather
“On Earth, we can predict if it is going to rain pretty much anywhere in the world very accurately, and space weather just isn’t there yet,” said Matt Mountain, president of the Association of Universities for Research in Astronomy, which manages the Inouye Solar Telescope. “Our predictions lag behind terrestrial weather by 50 years, if not more. What we need is to grasp the underlying physics behind space weather, and this starts at the Sun, which is what the Inouye Solar Telescope will study over the next decades.”
Solar magnetic fields constantly get twisted and tangled by the motions of the Sun’s plasma. Twisted magnetic fields can lead to solar storms that can negatively affect our technology-dependent modern lifestyles. During 2017’s Hurricane Irma, the National Oceanic and Atmospheric Administration reported that a simultaneous space weather event brought down radio communications used by first responders, aviation and maritime channels for eight hours on the day the hurricane made landfall.
Finally resolving these tiny magnetic features is central to what makes the Inouye Solar Telescope unique. It can measure and characterize the Sun’s magnetic field in more detail than ever seen before and determine the causes of potentially harmful solar activity.
“It’s all about the magnetic field,” said Thomas Rimmele, director of the Inouye Solar Telescope. “To unravel the Sun’s biggest mysteries, we have to not only be able to clearly see these tiny structures from 93 million miles away but very precisely measure their magnetic field strength and direction near the surface and trace the field as it extends out into the million-degree corona, the outer atmosphere of the Sun.”
Better understanding the origins of potential disasters will enable governments and utilities to better prepare for inevitable future space weather events. It is expected that notification of potential impacts could occur earlier — as much as 48 hours ahead of time instead of the current standard, which is about 48 minutes. This would allow for more time to secure power grids and critical infrastructure and to put satellites into safe mode.