The planetary trio has begun! That’s when three planets fit within a circle with a 5-degree, or smaller, diameter. Jupiter, Venus and Mercury meet that definition of a planetary trio from May 24-29, 2013. And they’ll be even closer – all be about 3 degrees apart – as evening dusk falls on May 25, 26 and 27. May 26 is the closest grouping of these three planets until the year 2021. If your sky is clear – and your horizon unobstructed – look for the planets in the west as soon as the sun sets on these May 2013 evenings. You’ll easily find the two brightest planets there: Venus and Jupiter. The innermost planet Mercury is fainter, but you’ll see it. Some are calling this late May 2013 event a triple conjunction, but a more fitting and descriptive name is planetary trio.

When and how do I look for the three planets?

Jupiter, Venus, Mercury daily viewing guide

Do I need any special equipment to see them?

How often do three planets appear together like this?

Triple conjunction? Planetary trio? Which?

Jupiter, Venus and Mercury as they’ll appear in western twilight on May 24, 2013.

Planetary trio – Venus, Jupiter, Mercury – at their closest on May 26, 2013. Illustration via bostonastronomy.net

The planets Venus and Jupiter as they appear in mid-May 2013.

The planets Mercury, Venus and Jupiter as they appear after sunset on May 23.

On May 26, you can see the closest grouping of three planets until the year 2021.

When and how do I look for the three planets? Start looking just after the sun goes down, about 30 minutes after sunset. Jupiter and Venus are now easily visible – both very bright – but they are low in the western twilight. Trees or tall buildings will block them from view. Mercury is also visible to the eye now. They are a very noticeable grouping, low in the twilight sky. Just be sure to look soon after the sun sets, because they’ll soon follow the sun below the western horizon.

Note that all three planets should be close enough together now for simultaneous binocular viewing. You can see them with the eye alone. Binoculars will enhance your enjoyment of the twilight scene.

Jupiter, Venus Mercury daily viewing guide

On May 24, Mercury passes Venus less than 2 degrees from Venus in right ascension. Around this time, the three planets will begin to look like a triangle in the twilight. Venus, Jupiter, and Mercury now all fit within a 5-degree circle and will stay that close together until May 29.

On May 26, the triangle of Venus, Jupiter and Mercury will be most compact, closer than you’ll see them again until 2021. Your thumb at arm’s length will almost cover them.

By May 27, the triangle is beginning to disperse, but wait … keep watching.

On May 28, Venus passes Jupiter in right ascension, at a distance of 1 degree. The two brightest worlds 1 degree apart! It’ll be an awesome sight.

Do I need any special equipment to see them? Not necessarily. The planets are bright and should be visible to your eye, assuming you’re looking toward an unobstructed western horizon in late May. But these planets will be setting soon after the sun. So if you have binoculars, do use them to spot the planets in the bright twilight and enhance your view. As soon as you locate Venus, look in that direction using binoculars. All three planets should fit simultaneously into the field of view of ordinary binoculars from May 25-27. Then, as twilight fades to night, set the binoculars aside and enjoy the view with your eye alone.

How about cameras and telescopes? Sure! If you have them, know how to use them and enjoy using them … give it a try. And if you get a good photo, please post it for all to see on EarthSky’s Facebook page, or at the EarthSky photo community on G+.

How often do three planets appear together like this? Seeing three planets so close together is fairly rare. It happened last in May 2011, and it won’t happen again until October 2015. This grouping is especially good because Venus and Jupiter are the brightest planets, and Mercury appears brighter, too, than most stars. The planetary trio will be visible even in places with heavy urban light pollution.

Triple conjunction? Planetary trio? Which? Strictly speaking, this is not a triple conjunction. A triple conjunction is an astronomical event that unfolds over several months. Traditionally, this term is used when two planets, or a planet and a star, appear due north-south of each other in the sky three times in a short space of time. That’s happening now, by the way, with Mercury and Venus. They are in conjunction (north-south on sky’s dome) on March 6, May 25 and June 20 this year. It’ll happen next in October-November 2013, when Mercury and Saturn will stage a true triple conjunction, appearing due north-south in the sky on October 10, October 28 and again on November 26.

In 2015, there will be another true triple conjunction, this time between the planets Venus and Jupiter (July 1, July 31, October 26).

But a triple conjunction is not what is happening in late May. Instead, there will be three separate planetary conjunctions in late May, over a few days:

Mercury and Venus on May 25, 2013 (4 UTC)

Mercury and Jupiter on May 27, 2013 (10 UTC)

Venus and Jupiter on May 28, 2013 (21 UTC)

See the difference?

Approximate relative sizes of Mercury, Venus and Jupiter. They look similar in our sky only because their distances from us are so different. During the last week of May, Mercury is about 9 light-minutes from Earth, Venus is 14 light-minutes away, and Jupiter is 51 light-minutes away. One light-minute is about 11 million miles (18 million km). Image via NASA

If all three planets had the same right ascension at once … wow! That’d definitely be a very cool triple conjunction. But I can’t recall that happening in my four decades of watching the sky. No idea how often it occurs, if ever.

Meanwhile, Jean Meeus of Belgium, recognized as a world authority in spherical and mathematical astronomy, has defined the term planetary trio as when three planets fit within a circle with a minimum diameter smaller than 5 degrees. All three planets will meet Meeus’ definition of a planetary trio from May 24-29, 2013. And they’ll be even closer – all be about 3 degrees apart – as evening dusk falls on May 25, 26 and 27. That’s about the width of your thumb at an arm length. It’ll be awesome. Don’t miss ‘em!

Bottom line: Jupiter, Venus and Mercury now fit within a circle whose diameter is less than 5 degrees wide on the sky’s dome. They’ll continue to be that close, or closer, through May 29. They’ll be a most compact triangle on May 26, closer than we’ll see them again until 2021. Some are also calling this a triple conjunction, but really it’s just three separate conjunctions happening over a few days. A better name for this event is planetary trio.

Details on May 25 planetary trio

Details on May 26 planetary trio (closest grouping of the three planets)

Details on May 27 planetary trio

Three planets adorn the western evening sky last week of May

The May 24-25 full moon moon is one day away from lunar perigee – the moon’s closest point to Earth for this month. By a newly coined popular definition, that makes this May full moon a supermoon. And as the line of sunsets has swept westward today, bringing night from the Far East to the Western Hemsiphere, we’ve enjoyed seeing your awesome supermoon photos. Thank you so much for posting them to the EarthSky Facebook page and Google+. We love them! Keep posting, and we’ll keep adding to the gallery as the sun sets – and the moon rises – further west.

Learn more details about tonight’s supermoon – and a slight penumbral eclipse tonight. Plus the star near tonight’s moon is Antares

What is a supermoon?

Read about the next supermoon: June 23, 2013

Abdulmajeed Alshatti wrote, “Enjoying the supermoon and the low tide. May 24,2013. Kuwait.” Because the moon is now full, and nearly at its closest to Earth, extra high and extra low tides can be expected.

Photo credit: Priya Kuman. She wrote, “24th May ’13 . Super Moon ……Flowers for the beautiful white bride of the sky — in Muscat, Masqat.”

The May 24-25, 2013 supermoon from Hyderabad, India. Photo credit: Kausor Khan

May 24-24, 2013 supermoon from Medan, Indonesia. Photo credit: Apple Saragih

May 24-25, 2013 supermoon. Malang, East Java, Indonesia. Photo credit: Bagoes Setiawon

May 24-25, 2013 supermoon from the Philippines. Photo credit: jv noriega

Photo credit: Raven Yu. She wrote,”Rising Full Flower Moon and an airplane (luck shot). 24 May 2013 17:53, Marikina City, Philippines. I was taking a photo of tonight’s moon when a plane flew through. I didn’t even notice it with my naked eyes.”

Photo credit: Frederick Dalpay

Send us your photos via EarthSky on Facebook, EarthSky’s photo community on Google+, and/or e-mail: images@earthsky.org.

By Elizabeth Smythe

UPDATED MAY 24, 2013 AT 1900 UTC (2 p.m. CDT). An M5-class solar flare on May 22, 2013 released a coronal mass ejection or CME. which has – as expected – now delivered a glancing blow to Earth’s magnetic field. The Advanced Composition Explorer (ACE) spacecraft – used by the Space Weather Prediction Center to provide warnings of these events – detected it beginning at about 1735 UTC (12:35 p.m. CDT) today. The Space Weather Prediction Center says to look for G1 (minor) geomagnetic storm levels over the next 24 hours. The estimate is for a 55% chance of polar geomagnetic storms in response to the strike. Aurora alert at high latitudes. Visit the Space Weather Prediction Center here for more updates.

Read more about the M-class flare on May 22

Activity on the sun’s surface gives us on Earth the most spectacular light show known to man: the aurora borealis or northern lights. They are bands of light, caused by charged solar particles’ interaction with Earth’s magnetic field. They glow, ripple and enchant those those lucky enough to see the phenomenon with their own eyes. Witnessing the aurora borealis is an experience not to miss. However, sightings are never guaranteed. Many factors can have an impact on whether the lights will appear. We’ve answered some of the most commonly asked questions, below.

How do I know when to look for the northern lights?

How far south can I see the lights?

Will a full moon affect my ability to see the northern lights?

What happens if it’s cloudy?

Can you hear the aurora?

Image via Weekend a la Carte

How do I know when to look for the northern lights? Good news. The sun itself will make the announcement. Aurorae are the result of solar activity, where colossal storms take place on the sun’s surface. Sometimes during these storms, coronal mass ejections (CMEs) – charged particles from the sun – are released. If the solar storm erupts in such a way that the resulting CME heads toward Earth, the likelihood of seeing an aurora increases. It takes several days for the charged particles to cross from the sun to Earth, so there is plenty of warning. When the charged particles arrive, they interact with Earth’s magnetic field, creating what is known as a geomagnetic storm. To what extent these charged particles will light up the night sky depends on a variety of factors including the strength of the CME plus whether it struck Earth’s magnetic field directly, or just delivered a glancing blow.

Spaceweather.com is a reliable and readable source of information about activity on the sun. Meanwhile, a great way to stay informed about the possibility of seeing an aurora on any given night is to access one of the numerous aurora alert websites: follow this link to find a list of aurora alert sites. Check them out when you get a chance; some update their forecasts live on Twitter.

Those keen to discover more about Earth’s magnetic field, meanwhile, might like to check out SAMNET, the sub-auroral magnetometer network from Lancaster University.

Image via Weekend a la Carte

How far south can I see the aurora borealis tonight? In general, the farther north you go, the greater the chances of seeing the northern lights. Alaska, northern Canada, Iceland, Greenland and Scandinavia are places where they’re often seen, but, you’ll be pleased to hear, the lights can on occasion extend down to lower latitudes. In the instance of very high geomagnetic activity, they lights can be seen as far south as England, the northern and even the southern U.S. (a sighting was even apparently once reported near the Mexican border), Northern Germany and Poland.

These more southerly sightings of the northern lights are rare, but as and when a strong solar storm occurs, you might be lucky enough to see the lights fairly far south.

Othewise, for some real-time aurora tracking, try Aurora Spy’s live data and aurora web cams page.

Will a full moon affect my ability to see the northern lights? Usually not. Naturally, a sky washed with bright moonlight won’t be as dark as it might otherwise be and thus the contrast between the aurora and night sky background won’t be as great. But only the very weakest aurorae will be completely drowned by the light of a full moon. Even in full moonlight, strong northern lights can still be seen clearly and photographed. In fact, LightsOverLapland.com photographer Chad Blakley, who regularly takes shots from the Abisko Aurora Sky Station in Swedish Lapland, has said that some of his best northern lights photographs have been taken when there was a full moon. For proof, see this earlier EarthSky article and marvel at the pictures that were snapped during a full moon.

What happens if it’s cloudy? The rule of thumb is, if you can see the stars, you can see the Northern Lights. Essentially, if the cloud cover is ‘thin’ enough not to conceal the twinkling stars, it shouldn’t make much difference. Thick cloud hovers underneath the aurora, so yes, it would block any sightings, unfortunately.

Image via Weekend a la Carte

Can you hear the aurora? While not a concern, this is a frequently asked question. And the answer is … we can’t be sure. Many people say they have heard a sound when witnessing the lights, but the upper atmosphere, according to the University of Alaska, is too thin to carry sounds waves. Plus the aurora itself is too far away. Yet still observers describe whistling, bristling, swooshing sound. The only way to know is to experience the aurora borealis for yourself!

About the Author: Brand Journalist and travel-obsessive Elizabeth Smythe writes this post on behalf of northern lights holiday specialists Weekend a la Carte. Check them out more insights and guides into this most magical of wonders.

Bottom line: Answers to commonly asked questions about seeing one of nature’s wonders: the aurora borealis or northern lights. Updated May 24, 2013 when a CME delivered a glancing blow to Earth’s magnetic field, providing an opportunity for possible high-latitude auroras.

Researchers from the Bergen fMRI Group at the University of Bergen (UiB) are working on how to help schizophrenics, who hear voices. The way they do this is by studying people who also hear voices, but who do not suffer from a mental illness. For a five-year period, the group is studying the brain processes causing people to hear voices. A recent report published in Frontiers in Human Neuroscience shows some of the group’s startling results.

Credit: Shutterstock / Andrii Kondiuk

– We have found that the primary auditory cortex of healthy people who hear voices, responds less to outside stimulus than the corresponding area of the brain in people who don’t hear voices, says Post Doctor Kristiina Kompus.

Kompus, who works at UiB’s Department of Biological and Medical Psychology, is lead author of the just published study.
Variations in cognitive control

The primary auditory cortex is the region of the brain that processes sound. Kompus’ study shows that healthy people who hear voices share some attributes with schizophrenics, as the cortical region in both groups reacts less to outside stimulus.

However, there is an important difference between people who hear voices. Whilst those with schizophrenia have a reduced ability to regulate the primary auditory cortex using cognitive control, those who hear voices but are healthy are able to do so.

– Because of this cognitive control, healthy people who hear voices are able to direct their attention outwards. This sets them apart from schizophrenics, who have a tendency to direct their attention inwards due to their decreased ability to regulate their primary auditory cortex, says Kompus before adding.

– These discoveries have brought us one step close to understanding the hallucinations of schizophrenics and why the voices become a problem for some people but not for others.
Many healthy people hear voices

So what is the next step for Kompus and her fellow researchers?

– We will do further research on the brain structure of people with auditory hallucinations. In particular, we wish to look at the brain’s networks that process outside voices. This is to establish whether these voice hallucinations and the outside voices occur in the same parts of the brain. We also wish to establish if hearing voices is a genetical trait, she says.

According to the researchers, approximately five per cent of us hear voices in the head, even if otherwise healthy. This number is based on research from several countries and surveys. For their own research, Kompus and her team used local media in Bergen to call for people who hear voices. The results were overwhelming, with around 30 people getting in touch with the researchers to register for the study.

Via University of Bergen

The vision of a society in which each inhabitant of the earth manages to consume only 2000 watts has already been around for 15 years. During this time, there has been a steady increase in environmental awareness in the West. Technology has become more efficient and there appears to be very little standing in the way of a sustainable lifestyle. However, as a study by Empa and the Federal Institute of Technology (ETH) Zurich now shows, Mr and Mrs Swiss are still a long way from achieving this.

Credit: Shutterstock Mopic

In 1998, researchers at the ETH Zurich developed an energy policy model that could provide energy for a growing world population and at the same time protect the environment. Through the use of efficient technologies and processes, the industrialised countries should reduce their energy consumption to 2000 watts per inhabitant – the global average. The resources freed up could then help to combat poverty and hunger worldwide, without a reduction in living standards for the Western countries. The city of Basel has been acting as a pilot region and, in 2008, the residents of Zurich expressed themselves through the ballot box in favour of striving for a 2000-watt society. At the same time as reducing electricity consumption, the aim is also to reduce emissions of greenhouse gases to the equivalent of one ton of CO2 per person per year.

Current per capita energy consumption in Switzerland meanwhile still exceeds the target for sustainability significantly, as the annual energy statistics from the Federal Office for the Environment (BAFU) show. However, such statistics use a “top-down” approach: they divide total consumption by the number of inhabitants. Dominic Notter and Hans-Jörg Althaus from Empa and Reto Meyer from the ETH Zurich therefore carried out a study which considers the environmental footprint of Switzerland “bottom-up”, i.e. based on the individual. The researchers were hoping to find households that already meet the criteria of the 2000-watt and/or 1-ton CO2 society. These examples could then be used to derive pioneering strategies for sustainability. The results of the study were published in the peer review scientific journal “Environmental Science & Technology”.

Through a combination of survey and lifestyle analysis, the researchers gained a uniquely detailed view into the different lifestyles of the Swiss population. 3369 households answered questions on living, transport, food and consumer goods. With the help of the “ecoinvent” database, which is administered by Empa, the researchers calculated the individual energy consumption, along with the resulting greenhouse gas emissions and the overall impact of each household on the environment.

Not a single household surveyed met the conditions of the 2000-watt society completely: even energy-efficient people produced too much CO2 emissions. The lowest individual value and the average of the most sustainable 10% of those surveyed are labelled.

Western lifestyle and the 2000-watt society – a contradiction?

The results were sobering: of 3369 households surveyed, not a single one met the conditions of the 2000-watt society. The economic theory that environmental impact increases with rising incomes and then decreases again was also not confirmed. Although it is true that energy consumption, emissions and environmental pollution do increase linearly with income, no reduction takes place (at even higher incomes).
Energy consumption among the households surveyed ranged from an “exemplary” 1400 watts per person to 20,000 watts – ten times the target value – with the average being 4200 watts. Overall, only two percent of those surveyed were below the 2000-watt threshold – and even they emitted far more than one ton of CO2. However, what is significant is that these low-energy households are found in every income bracket. If households with an above-average income only consume 2 kW of energy, the goal of a 2000-watt society is achievable: low energy consumption is possible with a high standard of living.

Around a quarter of the energy is consumed as electricity – therefore a massive reduction in overall consumption cannot be achieved simply by using more energy-efficient appliances. This is because a large part of the energy goes into heating and transport. The low-energy households scored particularly well in precisely these categories. Thus, the heated area per person was small and the heating requirement was relatively low. In terms of transport, such households were likewise very restrained: they limited themselves in terms of the amount of car driving and flying they did.

Although the average environmental impact of those surveyed is relatively low, it exceeds the guideline of the 2000-watt society by several times. The highest recorded energy consumption is even ten times higher than the recommended level.

It is thus in the area of living and transport behaviour that researchers see the most potential for improvement. Even in low-energy households, the heated area per person is too large. Transport, particularly by car and plane, accounts for almost half the greenhouse gas emissions and causes serious environmental pollution: the sources of energy used in this area are primarily fossil fuels.

Doing without is unavoidable

Researchers believe that the transformation of our society into a sustainable 2000-watt society is possible – but only with “the greatest possible effort”. However, reducing greenhouse gas emissions is far more difficult. For this, Switzerland would have to obtain 80 percent of its total energy from low-carbon sources. With the closure of the nuclear power stations, this means renewable energies – and not just for electricity, but also for heating and transport. This would require major technical advances – and a change in lifestyle, according to the study.

The ambitious sustainability target is only achievable if individuals and the state strive towards a sustainability strategy together. This calls for action such as intelligent town planning that reduces the need for travel and political measures that promote environmentally friendly behaviour. A sustainable lifestyle is characterised by frugality, so although we can maintain our quality of life, it is necessary to forego extravagance. By living in a smaller heated area, limiting the use of transport and avoiding excessive consumption of goods and services, according to Notter, everyone could do their bit for sustainability.

Via EMPA

Three planets close together in west this evening!

In 2013, the May full moon presents the third full moon after the March equinox. In North America we often call this particular full moon the Flower Moon, Rose Moon or Strawberry Moon. That star by tonight’s full moon is Antares, the brightest star in the constellation Scorpius the Scorpion. Plus the moon is one day away from lunar perigee – the moon’s closest point to Earth for this month. By a newly coined popular definition, that makes this May 24-25 full moon a supermoon. And the moon will undergo an extremely minor penumbral lunar eclipse tonight. With a penumbral eclipse magnitude of 0.0158, just 0.5 arc-minutes of the moon’s southern limb will pass into Earth’s pale penumbral shadow. It’s such a shallow eclipse that it’ll be mainly of academic interest and very difficult to detect. For more about the May 2013 lunar eclipse, click here.

What will most of us actually see tonight? Nothing unusual. Just the same wonderful full moon we see every month. Enjoy it.

What is a supermoon?

Read about the next supermoon: June 23, 2013

When exactly is the May 2013 full moon?

Three planets close together in west this evening!

Full moon mirrors sun’s path for six months hence

Our friend Jv Noriega in Manila, Philippines sent in this photo of tonight’s supermoon. Thanks, Jv!

When exactly is the May 2013 full moon? The May 2013 full moon falls at the same instant all over the world: May 25 at 4:25 Universal Time.

Clock time and/or date for this full moon – and every full moon – will vary by time zone. For London, the moon turns will at 5:25 a.m. BST on the morning of May 25; that means the moon will appear more full on the night of May 24-25 than on the night of May 25-26. Likewise, for the U.S. East Coast, the moon turns full on May 25 at 12:25 a.m. EDT. Meanwhile, for all places to the west of the U.S. Eastern Daylight Time zone, the moon turns full not on May 25 … but on May 24 at 11:25 p.m. CDT, 10:25 p.m. MDT and 9:25 p.m. PDT.

Technically speaking, the moon turns full at the instant that the moon lies most opposite the sun for the month. For general reference, though, we can say the moon is full all night long. Because the May 24-25 moon stays more or less opposite the sun throughout the night, watch for the full moon to rise in the east around sunrise, climb highest up in the sky around midnight and to set in the west around sunrise.

As seen from most of the world – when the moon rises on the evening of May 25 – it’ll be a waning moon.

The evening planets – Mercury, Venus and Jupiter – as they appear on May 24. They set shortly after sunset whereas the full moon stays out all night long on May 24/25. For North America, Mercury and Venus are in conjunction on the evening of May 24.

Three planets close together in west this evening! Don’t spend all your time moon gazing this evening. Be sure to look toward the western sky as soon as the sun sets for three planets, Mercury, Venus and Jupiter. They are now forming a cool planetary trio – which some are, mistakenly, calling a triple conjunction. In other words, these three planets are located within a circle on the sky’s dome whose diameter is less than 5 degrees. Clouded out tonight and can’t see the planetary trio? Never fear. It’ll last through May 29. Read more about the planetary trio here.

Photo of the planetary threesome over Lake Michigan after sunset May 23, 2013, courtesy of Rick Trommater. Thank you Rick! From left to right: Jupiter, Venus and Mercury. View larger

Full moon mirrors sun’s path for six months hence Any full moon mirrors the sun’s path across the sky for six months hence. As seen from the Northern Hemisphere, tonight’s full moon will follow the low path of the late autumn sun; as viewed from southerly latitudes, the moon will follow the lofty path of the late springtime sun.

Bottom line: Full moon for May 2013 falls during the night of May 24-25. For most of us around the world, the moon will appear more full on the night of the 24th than on the 25th. This May 2013 full moon is one day away from perigee – its closest point to Earth – and so will be called a supermoon. There is a slight penumbral eclipse tonight that’s extremely difficult to detect and mainly of academic interest. We’ll all see a bright full-looking moon tonight near the bright red star Antares in the constellation Scorpius!

What’s a supermoon? We confess: before a few years ago, we in astronomy had never heard that term. To the best of our knowledge, the term supermoon was coined by the astrologer Richard Nolle over 30 years ago. The term is only now coming into popular usage. Nolle has defined a supermoon as:

… a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.

That’s a pretty generous definition and allows for many supermoons. The first “super” full moon, for 2013, is coming up on the night of May 24-25. By this definition, according to Nolle:

There are 4-6 supermoons a year on average.

And indeed the Farmers Almanac for 2013 has now adopted the term supermoon, saying there will be three supermoons in a row coming up over these next three months in 2013: May 24-25, June 23, July 22.

Read more about the May 24-25 supermoon here.

Read more about the June 23 supermoon here.

What did astronomers call these moons before we called them supermoons?

Perigee full moon is a special kind of supermoon

So what exactly is a supermoon?

How many supermoons in 2013?

What does a supermoon look like? Astronomers say you can’t really detect any difference with your eye between a supermoon and any ordinary full moon. This great moon photo from EarthSky Facebook friend Rebecca Lacey in Cambridge, Idaho.

Photographs or other instruments can tell the difference between a supermoon and ordinary full moon. The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Image by Marco Langbroek of the Netherlands via Wikimedia Commons.

What did astronomers call these moons before we called them supermoons? We called them a full moon, or a new moon, at perigee. The moon is full, or opposite Earth from the sun, once each month. It’s new, or more or less between the Earth and sun, every month. And, every month, as the moon orbits Earth, it comes closest to Earth. That point is called perigee. The moon always swings farthest away once each month; that point is called apogee. No doubt about it. Supermoon is a catchier term than perigee full moon.

We first became familiar with the supermoon label in the year 2011 when the media used supermoon to describe the full moon of March 19, 2011. On that date, the full moon aligned with proxigee – the closest perigee of the year – to stage the closest, largest full moon of 2011.

Perigee full moon is a special kind of supermoon More often than not, the one day of the year that the full moon and perigee align also brings about the year’s closest perigee (also called proxigee). Because the moon has recurring cycles, we can count on the full moon and perigee to come in concert in periods of about one year, one month and 18 days.

Therefore, the full moon and perigee realign on March 19, 2011; May 6, 2012; June 23, 2013; August 10, 2014; September 28, 2015; November 14, 2016, and January 2, 2018. There won’t be a perigee full moon in 2017 because the full moon and perigee won’t realign again (after November 16, 2016) until January 2, 2018. By the way, all the full moons listed above are proxigee full moons.

So what exactly is a supermoon? To be called a supermoon, the full or new moon doesn’t actually have to align with perigee, in which case we would call it a perigee full moon or perigee new moon. (There won’t be a perigee new moon in 2013, because the perigee new moon happens in December 2012 and then in January 2014.)

By definition, a supermoon only has to be a new or full moon “at or near (within 90% of) its closest approach to Earth.” That means we have a number of supermoons in the span of one year.

How many supermoons in 2013? In 2013, according to the Farmer’s Almanac, there are only three supermoons, but we figure there are five and that the most super of the 2013 supermoons is the one on June 23.

In 2013, the moon comes closest to Earth on June 23 (356,991 kilometers) and swings farthest away on July 7 (406,490 kilometers). That’s a difference of 49,499 kilometers (406,490 – 356,991 = 49,499). Ninety percent of this 49,499-figure equals 44,549.1 kilometers (0.9 x 49,499 = 44,549.1). Presumably, any new or full moon coming closer than 361,940.9 kilometers (406,490 – 44,549.1 = 361,940.9) would be “at or near (within 90% of) its closest approach to Earth.” In other words, that’s my understanding of what supermoon means.

If I figured everything correctly, that gives us a total of 5 supermoons in 2013: three full moons (May 25, June 23 and July 22) and two new moons (January 11 and December 3).

However, the perigee full moon on June 23 will give us the most “super” supermoon of them all!

Bottom line: The term supermoon doesn’t come from astronomy. It’s comes from astrology, and the definition is pretty generous so that there are 4 to 6 supermoons each year. This post explains what a supermoon is, how many will occur in 2013, and which moon is the most “super” of all the 2013 supermoons.

This is so awesome… You can see him laughing!

A powerful 8.3-magnitude earthquake struck Russia’s Far East with tremors felt as far away as Moscow, which was about 7,000 kilometers (4,400 miles) west of the epicenter. The earthquake took place in the Sea of Okhotsk, the western Pacific Ocean. Emergency agencies in the Far East issued a tsunami warning for Sakhalin and the Kuril islands, but lifted it soon afterwards. Details of the quake, from the USGS, are below:

Event Time
2013-05-24 05:44:49 UTC
2013-05-24 15:44:49 UTC+10:00 at epicenter
2013-05-24 00:44:49 UTC-05:00 system time
Location

54.874°N 153.280°E

Depth=608.9km (378.4mi)

Nearby Cities
362km (225mi) WSW of Esso, Russia
383km (238mi) WNW of Yelizovo, Russia
400km (249mi) NW of Vilyuchinsk, Russia
406km (252mi) WNW of Petropavlovsk-Kamchatskiy, Russia
2374km (1475mi) NNE of Tokyo, Japan

This area – located on the Ring of Fire – is one of the most seismically active in the world.

According to the Huffington Post:

Russian news agencies reported that residents of Petropavlovsk-Kamchatsky on the Kamchatka peninsula in the Okhotsk Sea felt the tremors for about five minutes. Residents ran out of the buildings. School children were evacuated.

Bottom line: 8.3-magnitude earthquake in Russia’s Far East with tremors felt as far away as Moscow. Tsunami warning issues then rescinded.

What is the Ring of Fire?

The U.S. Geological Survey (USGS) reported a 5.7-magnitude earthquake in northern California last night (May 23 at 8:47 p.m. Pacific Daylight Time. The quake happened 113 miles (182 km) north-northeast of Sacramento, California. We are not seeing any reports of injuries or damages. Details of the quake below:

Event Time
2013-05-24 03:47:08 UTC
2013-05-23 20:47:08 UTC-07:00 at epicenter
2013-05-23 22:47:08 UTC-05:00 system time

Location
40.190°N 121.061°W

Depth=11.0km (6.8mi)

Nearby Cities
11km (7mi) WNW of Greenville, California
43km (27mi) SW of Susanville, California
60km (37mi) NE of Magalia, California
67km (42mi) NE of Paradise, California
159km (99mi) NW of Carson City, Nevada

More details about the May 23, 2013 California earthquake here.

A 4.9-magnitude quake struck a few hours later, just after 1 a.m. on May 24. Read about the aftershock here.

May 23, 2013 5.7-magnitude earthquake in northern California.

Bottom line: 5.7-magnitude earthquake and 4.9-magnitude aftershock in northern California on May 23-24, 2013.