Solar Cycle 24 is the 24th solar cycle since 1755, when recording of solar sunspot activity began. It is the current solar cycle, and began on 8 January 2008. It is predicted that Solar Cycle 24 will peak in May 2013 with 90 sunspots, which would be the fewest since solar cycle 16.
According to NASA, the intensity of geomagnetic storms during Solar Cycle 24 may be elevated by a large breach in Earth’s magnetic field which was discovered by the THEMIS spacecraft in 2008. A 20-fold increase in particle counts that penetrate the Earth’s magnetic field may be expected.
Solar Cycle 24 has been the subject of various hypotheses and commentary pertaining to its potential effects on Earth.
Without suggesting that the next solar maximum will be unusually destructive to Earth, astrophysicist Michio Kaku has taken advantage of the media focus on the 2012 phenomenon to draw attention to the need to develop strategies for coping with the terrestrial damage that solar activity can inflict. He asserts that governments should ensure the integrity of electrical infrastructures, so as to prevent a recurrence of disruption akin to that caused by the solar storm of 1859.
Solar Cycle 24 has also been cited by proponents of the 2012 phenomenon as evidence of a cataclysmic doomsday event aligned with their respective views.
The current solar cycle is currently the subject of research due, as it does not appear to be generating sunspots in the manner which would be expected. Sunspots did not begin to appear immediately after the last minimum (in 2008) and although they started to reappear in late 2009, they are at significantly lower than anticipated.
August 2010 Coronal mass ejections
On August 1, 2010, scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) observed a series of four large CMEs emanating from the Earth-facing hemisphere by analyzing images recorded at NASA’s Solar Dynamics Observatory. The observed velocities of the ejecta varied between 670,560 m/s and 1,118,000 m/s (metre per second), and were expected to reach the Earth’s geomagnetic field sometime between August 4 and early August 5. As of 05:00 UTC August 4, the estimated time of arrival of the series was as follows:
Wednesday, August 4 – 07:00 UTC
Wednesday, August 4 – 17:00 UTC
Thursday, August 5 – 00:00 UTC
Thursday, August 5 – 06:00 UTC[12]
All four ejections were described as large and, according to scientists, possessed enough energy to cause aurorae to be observed by naked eye in non-polar regions. According to reports, aurorae would be visible at night toward the poleward horizon in temperate latitudes between 45° to 50°, and near overhead in regions closer to the poles. The initial coronal mass ejection of August 1, named Sunspot 1092, was big enough to be seen without the aid of a solar telescope.
Aside from the visual effects of this CME series, scientists warned that electric impulses caused by disruptions in the magnetic field due to the ionized particles may damage infrastructure such as power grids and telephone lines not adequately protected against induced magnetic current.
It has also been reported that several Earth-orbiting satellites may be in similar danger. According to Leon Golub, an astronomer at CfA: This eruption is directed right at us and is expected to get here early in the day on August 4. It’s the first major Earth-directed eruption in quite some time.
When such an expulsion reaches Earth, it interacts with the planet’s magnetic field and can create a geomagnetic storm. Solar particles stream down the field lines toward Earth’s poles. Those particles crash with atoms of nitrogen and oxygen in the atmosphere, which then glow like little neon signs. Sky watchers in the northern U.S. and other countries should look toward the north late Tuesday or early Wednesday for rippling “curtains” of green and red light.
Aurorae observations: In the early morning hours of August 4, 2010 aurorae occurred in the northern hemisphere that were visible at latitudes as far south as Michigan and Wisconsin in the United States, and Ontario, Canada near latitude 45° North (see image at right). European observers reported sightings as far south as Denmark near latitude 56° North. The aurorae were reportedly green in color due to the interaction of the solar particles with oxygen atoms in the relatively denser atmosphere of southern latitudes. This, however, was only the first wave of solar wind; the third and last was expected for the evening of August 5, but missed Earth entirely.
The solar storm of 1859, also known as the Solar Superstorm, or the Carrington Event, was the most powerful solar storm in recorded history. It occurred during solar cycle 10.
On September 1–2, 1859, the largest recorded geomagnetic storm occurred. Aurorae were seen around the world, most notably over the Caribbean; also noteworthy were those over the Rocky Mountains that were so bright that their glow awoke gold miners, who began preparing breakfast because they thought it was morning.
Telegraph systems all over Europe and North America failed. Telegraph pylons threw sparks and telegraph paper spontaneously caught fire. Some telegraph systems appeared to continue to send and receive messages despite having been disconnected from their power supplies.
From August 28, 1859 until September 2, numerous sunspots and solar flares were observed on the sun. Just before noon on September 1, the British astronomer Richard Carrington observed the largest flare, which caused a massive coronal mass ejection (CME) to travel directly toward Earth, taking 18 hours. This is remarkable because such a journey normally takes three to four days. It moved so quickly because an earlier CME had cleared its way.
Ice cores show evidence that events of this magnitude – as measured by high-energy proton radiation, not geomagnetic effect – occur approximately once per 500 years, with events >1/5 as large occurring several times per century. Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported
Solar Cycle 24 Begins – NASA Science
“On January 4, 2008, a reversed-polarity sunspot appeared—and this signals the start of Solar Cycle 24,” states David Hathaway of the Marshall Space Flight Center. Solar activity waxes and wanes in 11-year cycles. Lately, we’ve been experiencing the low ebb, “very few flares, sunspots, or activity of any kind,” stated Hathaway. “Solar minimum is upon us.”
The previous solar cycle, Solar Cycle 23, peaked in 2000-2002 with many furious solar storms. That cycle decayed as usual to the present quiet leaving solar physicists little to do other than wonder, when would the next cycle begin?The answer is now.
“New solar cycles always begin with a high-latitude, reversed polarity sunspot,” explains Hathaway.
”Reversed polarity” means a sunspot with opposite magnetic polarity compared to sunspots from the previous solar cycle. “High-latitude” refers to the sun’s grid of latitude and longitude. Old cycle spots congregate near the sun’s equator. New cycle spots appear higher, around 25 or 30 degrees latitude.
The sunspot that appeared on January 4th fits both these criteria. It was high latitude (30 degrees N) and magnetically reversed. NOAA named the spot AR10981, or “sunspot 981″ for short. Sunspot 981 was small–only about as wide as Earth, which counts as small on the grand scale of the sun–and it has already faded away. But its three day appearance on Jan. 4-6 was enough to convince most solar physicists that Solar Cycle 24 is underway.
Doug Biesecker of NOAA’s Space Weather Prediction Center in Boulder, Colorado, likens sunspot 981 “to the first robin of spring. There’s still snow on the ground, but the seasons are changing.” Last year, Biesecker chaired the Solar Cycle 24 Prediction Panel, an international group of experts from many universities and government agencies. “We predicted that Solar Cycle 24 would begin around March 2008 and it looks like we weren’t far off,” he stated.
The first auroras of the new solar cycle, were photographed Jan. 4, 2008, by Calvin Hall of Palmer, Alaska. The onset of a new solar cycle is significant because of our increasingly space-based technological society.
“Solar storms can disable satellites that we depend on for weather forecasts and GPS navigation,” states Hathaway. Radio bursts from solar flares can directly interfere with cell phone reception while coronal mass ejections (CMEs) hitting Earth can cause electrical power outages. “The most famous example is the Quebec outage of 1989, which left some Canadians without power for as much as six days.”
Air travel can be affected, too. Every year, intercontinental flights carry thousands of passengers over Earth’s poles. It’s the shortest distance between, say, New York and Tokyo or Beijing and Chicago. In 1999, United Airlines made just twelve trips over the Arctic. By 2005, the number of flights had ballooned to 1,402. Other airlines report similar growth.
“Solar storms have a big effect on polar regions of our planet,” states Steve Hill of the Space Weather Prediction Center. “When airplanes fly over the poles during solar storms, they can experience radio blackouts, navigation errors and computer reboots all caused by space radiation.” Avoiding the poles during solar storms solves the problem, but it costs extra time, money and fuel to “take the long way around.”
Now for the good news: More solar storms also means more auroras, “the greatest show on Earth.” During the last solar maximum, Northern Lights were spotted as far south as Arizona, Florida and California. Not so long ago, only visitors to the Arctic regularly enjoyed auroras, but with increasing attention to space weather and constantly improving forecasts, millions of people at all latitudes will know when to go out and look.
Much of this is still years away. “Intense solar activity won’t begin immediately,” notes Hathaway. “Solar cycles usually take a few years to build from solar minimum (where we are now) to Solar Max, expected in 2011 or 2012.” It’s a slow journey, but we’re on our way.
