about-the-sun

How strong can a geomagnetic storm be?

kolinski — Wed, 02 Feb 2022 19:50:43 +0000

How strong can a geomagnetic storm be? kolinski Wed, 02/02/2022 - 12:50

Aurora forecast after a strong geomagnetic storm on September 13, 2014.

A geomagnetic superstorm from the Sun can be very strong but it does not happen frequently. However just like with natural disasters like fires and tornados we need to be prepared. Scientists measure the strength or energy of a geomagnetic storm in Watts, which measures how much energy is transferred in 1 second. A superstorm can dump as much as 5,000 GW (10^9 W) into Earth’s atmosphere at its peak time. That is more than the energy consumption rate of the US (~3,300GW).

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What protects the Earth from the Sun’s space weather?

kolinski — Wed, 02 Feb 2022 19:37:36 +0000

What protects the Earth from the Sun’s space weather? kolinski Wed, 02/02/2022 - 12:37

The Earth's magnetosphere.

NASA/Goddard/Aaron Kaase

Earth sits within a bubble formed by Earth’s strong magnetic field. This magnetic field is constantly exposed to the wind from the Sun and therefore shaped like a teardrop with a tail pointing away from Earth and Sun. This protective bubble is called the magnetosphere, and is responsible for deflecting most of the high energy particles from Earth.

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What is space weather?

kolinski — Wed, 02 Feb 2022 18:57:13 +0000

What is space weather? kolinski Wed, 02/02/2022 - 11:57

Space weather from Sun to Earth, in this case caused by a coronal mass ejection (CME).

NASA

Space weather is a branch of space physics and heliophysics, the science of understanding the Sun and its connection with the solar system.

Like Earth's weather, space weather describes the variable conditions in the space environment between Earth and the Sun. Extreme space weather can impact our technology in space such as satellites, but also interfere with communication systems, global navigation satellite systems such as GPS, and damage our power electric power grid. Therefore space weather is monitored continuously to protect our infrastructure.

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How does the Sun affect our climate?

kolinski — Wed, 02 Feb 2022 18:42:59 +0000

How does the Sun affect our climate? kolinski Wed, 02/02/2022 - 11:42

The Sun drives the weather on planet Earth. The winds and circulation of ocean patterns are all affected by the Sun's energy output. The differential heating of the planet, due to the tilt of the rotation axis of the Earth with respect to the Sun, generates the winds and major ocean currents as well as providing us with our seasons. Furthermore, it is believed that the 11-year solar cycle has an impact on our climate.

Ocean currents.

JPL-CALTECH/NASA

An excellent review of the climatic impact of the Sun on Earth can be found at the Space Weather Prediction Center (NOAA).

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How does the Sun affect communications?

kolinski — Wed, 02 Feb 2022 18:34:56 +0000

How does the Sun affect communications? kolinski Wed, 02/02/2022 - 11:34

Communication satellite.

Wikipedia

In our technology-based economy we depend heavily on satellites and various forms of high frequency communication systems. Communications and navigation systems used by commercial airliners can be affected by geomagnetic storms which are caused by solar activity. Geomagnetic storms can actually cause the atmosphere of Earth to expand, affecting satellite orbits. An excellent review of these issues can be found at the Space Weather Prediction Center (NOAA).

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What are the aurorae?

kolinski — Wed, 02 Feb 2022 18:09:25 +0000

What are the aurorae? kolinski Wed, 02/02/2022 - 11:09

The northern lights occur near the north pole of earth. The phenomena is known as the aurora borealis when it occurs in the northern hemisphere and as the aurora australis when it occurs in the southern hemisphere. The name aurora borealis comes from the Latin for northern dawn.

The mechanism for aurorae.

We now know what causes these spectacular displays in the sky. The interaction of the solar wind with the geomagnetic field of the Earth cause energetic particles (primarily electrons and protons) — a million tons of it — to enter into the Earth's upper atmosphere. There they interact with molecules of nitrogen and oxygen to produce the red and green light seen in the auroral phenomena.

Auroral phenomena have been observed on other planets of our solar system, including Jupiter, Saturn, and even Mars.

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How does the Sun work?

kolinski — Wed, 02 Feb 2022 17:28:50 +0000

How does the Sun work? kolinski Wed, 02/02/2022 - 10:28

The Sun is a giant, natural thermonuclear reactor that converts hydrogen to helium in its core to produce the heat we sense on our faces as sunshine.

The outward pressure of fusion balances the inward force of gravity.

https://cnx.org/contents/22C4lQHJ@8/Nuclear-Fusion

Why does this reactor not explode as a thermonuclear bomb? The Sun is held together in an equilibrium state by the mutual gravitational attraction between all its atoms acting to compress the solar center. These gravitational forces produce and contain the nuclear reactions taking place there. The solar atmosphere outside the energy generating core adjusts itself to carry the enormous amount of energy that emerges from the surface in the form of radiation.

This is the basic idea behind the existence of all stars beginning with gravitational attraction and compression of a gas cloud to the beginning of nuclear energy generation and, finally, to the exhaustion of the nuclear fuel and death of the star.

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What tools do scientists use to study the Sun?

kolinski — Wed, 02 Feb 2022 16:49:18 +0000

What tools do scientists use to study the Sun? kolinski Wed, 02/02/2022 - 09:49

Scientists study the Sun using satellites and ground-based telescopes, observing everything from the sun's outer atmosphere to its surface and interior.

Artist rendering of Solar Dynamics Observatory (SDO) in orbit (launched in 2010).

NASA

Since the magnetic field of the Sun is so important, scientists observe the Sun in as many wavelengths as possible near the various emission and absorption lines of atoms near the Sun's surface.

Since we cannot see the interior of the Sun, scientists must use indirect methods. For instance, if you strike an object, you can tell something about its substance by the way it vibrates in response (a bell will ring, and jello will just wiggle). The same applies to the Sun. The movement of material inside the Sun (such as dynamic flares and CMEs) produces pressure waves that make the Sun’s surface vibrate. With very accurate telescopes the vibrations can be measured, and then carefully analyzed to determine properties of the interior. This is a very exciting new field, helioseismology.

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Why is it important to study the Sun?

kolinski — Wed, 02 Feb 2022 16:19:32 +0000

Why is it important to study the Sun? kolinski Wed, 02/02/2022 - 09:19

Variations of the Sun's output do occur, and these affect the Earth's climate. Indeed, tree ring studies and ice core studies indicate a correlation between Earth's ice ages and the Sun's activity.

A large coronal mass ejection (CME) blasting solar material into space.

SOHO (ESA/NASA)

The Sun’s powerful eruptions can also disrupt life on Earth. Coronal mass ejections (or CMEs) occur when large amounts of material are ejected from the Sun’s corona into interplanetary space. These CMEs can carry a million tons of material out towards the planets at a million miles an hour (almost a billion kg at 27 million m/s). When a portion of this material reaches the Earth's outer atmosphere, it impacts satellites, perturbing their orbits, scoring their surfaces, and disrupting communications. The solar material can slide down the Earth's magnetic field lines and cause the phenomenon known as aurora, and also burn out power grids. CMEs occur perhaps once a month or so during solar minimum, and up to twice or more a day at solar maximum (read more about the solar cycle).

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What are some historical observations of the Sun?

kolinski — Wed, 02 Feb 2022 15:45:18 +0000

What are some historical observations of the Sun? kolinski Wed, 02/02/2022 - 08:45

The Sun has been studied by humans for a long time. Eclipses were likely first recorded prior to 1948 B.C. Astronomers in China noticed sunspots several thousand years ago: the I-Ching or "Book of Changes," which dates back to the 12th century B.C., mentions a "Ri Zhong Jian Mei," which means "a obscuration was seen within the Sun". The first written record of a sunspot sighting dates to 28 B.C (by Chinese astronomers).

Telescopic observations of the Sun's surface began around 1610. It was at this time that the sunspots could be systematically observed and were, by Galileo, Fabricius, Scheiner and Harriot. For Galileo this was actually unlucky. Western religions expected the Sun to have no "blemishes" and the observations of sunspots did not further his career at all. He was forced to recant and placed under house arrest.

Nevertheless, observations of sunspots and the Sun continued. Around 1645 the sunspot count became very low until 1715. During these 70 years, there were likely less than 15 sunspots observed. These days, the minimum number observed per year is more like 15, even when the Sun is in its "inactive" phase. Interestingly, Europe had cooler than normal temperatures at this same time. So there is some indication that variations occurred in the Sun at the same time which cooled Earth's climate. This time period is referred to as the "Little Ice Age", and the sunspot absence as the Maunder Minimum.

400 years of sunspot observations.

Wikipedia

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about-the-sun

How strong can a geomagnetic storm be?

Category

What protects the Earth from the Sun’s space weather?

Category

What is space weather?

Category

How does the Sun affect our climate?

Category

How does the Sun affect communications?

Category

What are the aurorae?

Category

How does the Sun work?

Category

What tools do scientists use to study the Sun?

Category

Why is it important to study the Sun?

Category

What are some historical observations of the Sun?

Category