Posted on by David Dickinson

April Lunacy: Getting Ready for the Full ‘Mini-Moon’

2015 Mini-Moon
The March 5th 2015 Mini-Moon. Image credit and copyright: Alan Dyer

Do you welcome the extra evening light of the Full Moon, or curse the additional light pollution? Either way, this week’s Full Moon on Friday April 22nd is special. It’s the smallest Full Moon of 2016, something we here at Universe Today have christened the Mini-Moon.

Mini-Moon 2016: This year’s Mini-Moon falls on April 22nd at 5:25 Universal Time (UT), just 13 hours and 19 minutes after lunar apogee the evening prior at 16:06 UT on April 21st. Though apogee on the 21st is 406,350 km distant – a bit on the far end, but the third most distant for the year by 300 km — this week’s Full Moon is the closest to apogee for 2016 time-wise. The 2015 Mini-Moon was even closer, in the 10 hour range, but you’ll have to wait until December 10th, 2030 to find a closer occurance.

Image credit and copyright:
The Mini-Moon versus the 2011 Supermoon. Image credit and copyright: Ken Lord.

What is the Mini-Moon, you might ask? As with the often poorly defined Supermoon, we like to eschew the ambiguous ‘90% of its orbit’ definition, and simply refer to it as a Full Moon occurring within 24 hours of lunar apogee, or its farthest point from the Earth in its orbit.

Fun fact: the 29.55 day period from perigee to perigee (or lunar apogee-to-apogee) is known as an anomalistic month.

Image credit: Dave Dickinson
Mini-Moons by year for the remainder of the decade. Note that the 2020 Full Moon is also the 2nd of the month… A ‘Mini-Blue Halloween Moon?’ Image credit: Dave Dickinson

Thank our Moon’s wacky orbit for all this lunacy. Inclined 5.14 degrees relative to the ecliptic plane, the Moon returns to the same phase (say, Full back to Full) every 29.53 days, known as a synodic month. The Moon can appear 33.5′ across during perigee, and shrink to 29.4′ across near apogee.

The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size. Wikimedia Commons graphic in the public Domain.
The appearance of the Moon through one synodic period. Note that in addition to rocking back and forth (libration) and side-to-side (nutation), the Moon appears to swell and shrink in size. Wikimedia Commons graphic in the Public Domain.

And don’t fear the ‘Green Moon,’ and rumors going ’round ye’ ole internet that promise a jaded Moon will occur in April or May; this is 100% non-reality based, seeking to join the legends of Super, Blood, and Full Moons, Black and Blue.

Image faked by: David Dickinson.
No. Just. No. Image faked by: David Dickinson.

The April Full Moon is also known as the Full Pink Moon to the Algonquin Indians. The April Full Moon, can, on occasion be the Full Moon ushering in Easter (known as the Paschal Moon) as per the rule established by the 325 AD council of Nicaea, stating Easter falls on the first Sunday after the first Full Moon after the fixed date of the Vernal Equinox of March 21st. Easter can therefore fall as late as April 25th, as next occurs on 2038. The future calculation of Easter by the Church gets the Latin supervillain-sounding name of Computus.

April 21st. Image credit: Stellarium
Looking east on the evening of April 21st. Image credit: Stellarium

Of course, the astronomical vernal equinox doesn’t always fall on March 21st, and to complicate matters even further, the Eastern Orthodox Church uses the older Julian Calendar and therefore, Easter doesn’t always align with the modern western Gregorian calendar used by the Roman Catholic Church.

The Moon can create further complications in modern timekeeping as well.

Here’s one wonderful example we recently learned of in our current travels. The Islamic calendar is exclusively based on the synodic cycle of the Moon, and loses 11 days a year in relation to the Gregorian solar calendar. Now, Morocco officially adopted Daylight Saving (or Summer) Time in 2007, opting to make the spring forward during the last weekend of March, as does the European Union to the north. However, the country reverts back to standard time during the month of Ramadan… otherwise, the break in the daily fast during summer months would fall towards local midnight.

You can see a curious future situation developing. In 2016, Ramadan runs from sundown June 5th, to July 4th. Each cycle begins with the sighting of the thin waxing crescent Moon. However, as Ramadan falls earlier, you’ll get a bizarre scenario such as 2022, when Morocco springs forward on March 27th, only to fall back to standard time six days later on April 2nd on the start of Ramadan, only to jump forward again one lunation later on April 30th!

Morocco is the only country we’ve come across in our travels that follows such a convoluted convention of timekeeping.

Fun fact #2: the next ‘Mini-Moon’ featuring a lunar eclipse occurs on July 27th 2018.

And the Spring Mini-Moon sets us up for Supermoon season six months later this coming October-November-December. Though lunar perigees less than 24 hours from Full usually occur as a trio, an apogee less than 24 hours from Full is nearly always a solitary affair, owing to the slightly slower motion of the Moon at a farther distance.

Don’t miss the shrunken Mini-Moon rising on the evenings of Thursday April 21st and Friday 22nd, coming to a sky near you.

Posted on by Fraser Cain

When Will Earth Lock to the Moon?

When Will Earth Lock to the Moon?

We always see the same side of the Moon. It’s always up there, staring down at us with its terrifying visage. Or maybe it’s a creepy rabbit? Anyway, it’s always showing us the same face, and never any other part.

This is because the Moon is tidally locked to the Earth; the same fate that affects every single large moon orbiting a planet. The Moon is locked to the Earth, the Jovian moons are locked to Jupiter, Titan is locked to Saturn, etc.

As the Moon orbits the Earth, it slowly rotates to keep the same hemisphere facing us. Its day is as long as its year. And standing on the surface of the Moon, you’d see the Earth in roughly the same spot in the sky. Forever and ever.

Forever and ever and ever... unless we finally manage to destroy the Moon. Credit: NASA/Goddard/Arizona State University
Because of tidal locking, you’d see Earth in roughly the same spot from the Moon forever. For-eh-ver. For-EH-VER. Credit: NASA / Goddard / Arizona State University

We see this all across the Solar System.

But there’s one place where this tidal locking goes to the next level: the dwarf planet Pluto and its large moon Charon are tidally locked to each other. In other words, the same hemisphere of Pluto always faces Charon and vice versa.

It take Pluto about 6 and a half days for the Sun to return to the same point in the sky, which is the same time it takes Charon to complete an orbit, which is the same time it takes the Sun to pass through the sky on Charon.

Since Pluto eventually locked to its moon, can the same thing happen here on Earth. Will we eventually lock with the Moon?

Before we answer this question, let’s explain what’s going on here. Although the Earth and the Moon are spheres, they actually have a little variation. The gravity pulling on each world creates love handle tidal bulges on each world.

And these bulges act like a brake, slowing down the rotation of the world. Because the Earth has 81 times the mass of the Moon, it was the dominant force in this interaction.

In the early Solar System, both the Earth and the Moon rotated independently. But the Earth’s gravity grabbed onto those love handles and slowed down the rotation of the Moon. To compensate for the loss of momentum in the system, the Moon drifted away from the Earth to its current position, about 370,000 kilometers away.

But Moon has the same impact on the Earth. The same tidal forces that cause the tides on Earth are slowing down the Earth’s rotation bit by bit. And the Moon is continuing to drift away a few centimeters a year to compensate.

It’s hard to estimate exactly when, but over the course of tens of billions of years, the Earth will become locked to the Moon, just like Pluto and Charon.

Pluto and Charon are tidally locked to each other. Credit: NASA/JHUAPL/SwRI
Pluto and Charon are tidally locked to each other. Credit: NASA / JHUAPL / SwRI

Of course, this will be long after the Sun has died as a red giant. And there’s no way to know what kind of mayhem that’ll cause to the Earth-Moon system. Other planets in the Solar System may shift around, and maybe even eject the Earth into space, taking the Moon with it.

What about the Sun? Is it possible for the Earth to eventually lock gravitationally to the Sun?

Astronomers have found extrasolar planets orbiting other stars which are tidally locked. But they’re extremely close, well within the orbit of Mercury.

Here in our Solar System, we’re just too far away from the Sun for the Earth to lock to it. The gravitational influence of the other planets like Venus, Mars and Jupiter perturb our orbit and keep us from ever locking. Without any other planets in the Solar System, though, and with a Sun that would last forever, it would be an inevitability.

It is theoretically possible that the Earth will tidally lock to the Moon in about 50 billion years or so. Assuming the Earth and Moon weren’t consumed during the Sun’s red giant phase. I guess we’ll have to wait and see.

Posted on by David Dickinson

Watch the Moon Occult Vesta and Aldebaran This Weekend

The Moon occults Aldebaran last lunation on March 14th as seen from India. Image credit and copyright: Rajneesh Parashar

So, did you miss yesterday’s occultation of Venus by the Moon? It was a tough one, to be sure, as the footpath for the event crossed Europe and Asia in the daytime. Watch that Moon, though, as it crosses back into the evening sky later this week, and occults (passes in front of) the bright star Aldebaran for eastern North America and, for Hawaii-based observers, actually covers the brightest of the asteroids, 4 Vesta. Continue reading “Watch the Moon Occult Vesta and Aldebaran This Weekend”

Posted on by David Dickinson

A Challenging Daytime Occultation of Venus for Europe

Do you see it? I 2% illuminated waning 'Old Moon,' 24+ hours from New. The April 6th Moon will be about as thin. Image credit: Dave Dickinson

Sometimes, the Universe seems bent on hiding the most glorious of events right in plain sight. Just a such an event occurs next week, when the slender waning crescent Moon occults the planet Venus for observers across Europe, the United Kingdom and northern Asia. Continue reading “A Challenging Daytime Occultation of Venus for Europe”

Posted on by Evan Gough

The Moon’s Other Axis

A six degree True Polar Wander occurred on the Moon due to ancient volcanic activity. Image: University of Arizona/James Tuttle Keane
A six degree True Polar Wander occurred on the Moon due to ancient volcanic activity. Image: University of Arizona/James Tuttle Keane

It’s tempting to think that the Moon never changes. You can spend your whole life looking at it, and see no evidence of change whatsoever. In fact, the ancients thought the whole Universe was unchanging.

You may have heard of a man named Aristotle. He thought the Universe was eternal and unchanging. Obviously, with our knowledge of the Big Bang, stellar evolution, and planetary formation, we know better. Still, the placid and unchanging face of the Moon can tempt us into thinking astronomers are making up all this evolving universe stuff.

But now, according to a new paper in Nature, the Moon’s axis of rotation is different now than it was billions of years ago. Not only that, but volcanoes may been responsible for it. Volcanoes! On our placid little Moon.

The clue to this lunar True Polar Wander (TPW) is in the water ice locked in the shadows of craters on the Moon. When hydrogen was discovered on the surface of the Moon in the 1990s by the Lunar Prospector probe, scientists suspected that they would eventually find water ice. Subsequent missions proved the presence of water ice, especially in craters near the polar regions. But the distribution of that water-ice wasn’t uniform.

You would expect to see ice uniformly distributed in the shadows of craters in the polar regions, but that’s not what scientists have found. Instead, some craters had no evidence of ice at all, which led the team behind this paper to conclude that these ice-free craters must have been exposed to the Sun at some point. What else would explain it?

The way that the ice in these craters is distributed forms two trails that lead away from each pole. They’re mirror images of each other, but they don’t conform with the Moon’s current axis of rotation, which is what led the team to conclude that the Moon underwent a 6 degree TPW billions of years ago.

The paper also highlights the age of the water on the Moon. Since the TPW, and the melting of some of the ice as a result of it, occurred some billions of years ago, then the water ice that is still frozen in the shadows of some of the Moon’s craters must be ancient. According to the paper, its existence records the “early delivery of water to the inner Solar System.” Hopefully, a future mission will return a sample of this ancient water for detailed study.

But even more interesting than the age of the ice in the craters and the TPW, to me anyways, is what is purported to have caused it. The team behind the paper reports that volcanic activity on the Moon in the Procellarum region, which was most active in the early history of the Moon, moved a substantial amount of material and “altered the density structure of the Moon.” This alteration would have changed the moments of inertia on the Moon, resulting in a TPW.

It’s strange to think of the Moon with volcanic activity viewable from Earth. I wonder what effect visible lunar volcanoes would have had on thinkers like Aristotle, if lunar volcanic activity had occurred during recorded history, rather than ending one billion years ago or so.

We know that events like eclipses and comets caused great confusion and sometimes upheaval in ancient civilizations. Would lunar volcanoes have had the same effect?

Posted on by Mark Mortimer

Book Review: The Chang’E-1 Topographic Atlas of the Moon

I like hiking. Particularly, I like wandering in places I’ve never been before. Sometimes only a map, a compass and a good sense of direction gets me returning to where I began.

Many people on Earth enjoy this simple pleasure. But what to do if you’re on the Moon?

Well, assuming you’ve got the right equipment, like a spacesuit, then all you’d need is a good map because, of course, compasses aren’t of much use. So which map do you use? Well, take a look at “The Chang’E-1 Topographic Atlas of the Moon” by Chunlai Li, Jianjun Liu, Lingli Mu, Xin Ren and Wei Zuo. This lovely, featured book will have you easily finding your way about the lunar surface.

“An atlas?” I hear you asking. “Who’s going to sit down and read an atlas?”  Good question, as I didn’t think I would either, but I definitely will use this book.

For me, a good atlas allows me to understand the shape of the land; almost to feel the topology without actually being there. When I hike, I use maps to find interesting outlooks, amazing drop-offs or dry land between swamps. On the Moon we certainly don’t have to worry about water features. But there are many other features that are at least interesting enough to warrant a particular nomenclature according to the International Astronomical Union. This book includes eleven of such nomenclatures.

For instance, there are the very dry Oceani, the Maria that hint at water courses, circular craters with astoundingly sharp edges and the knife edge rimae that slice along. How do I know of these descriptions? Simple. I look at the maps in the book. There are 188 maps each on their own page; all of them presenting an equal and fine finishing. And they include the complete Moon surface, with a space resolution of 500m, a horizontal accuracy of 192m and vertical of 120m. Actually, that’s most of the book. There’s an appendix. It includes a list of 3,698 features placed on the maps with each feature having; its name, its latitude, its longitude, its size in kilometres and its page. With this appendix, one can quickly and easily find the common lunar geographic features. There are a few pages of introduction. And that’s all. It’s just like an atlas should be; straightforward, simple and to the point.

I bet you’re wondering about where the data came from? The title says it all. It’s from China’s Chang’E-1 probe. This book is a re-issue in English of their initial production of 2012. Nicely located in the preamble is a description of the data processing. This includes specifications of the CCD camera, the characteristics of the probe’s orbit and the actual data processing. It’s apparently no mean feat, as the data came from a three-line array CCD stereo imager and resulted in the Mercator or Azimuthal projections. Some additional information is at this link (in English).

However, what’s most impressive for me is that this book shows that China is actively and capably adding to the scientific knowledge of space. Yet, in acknowledgement to lunar mapping already done, the authors included a very informative history of lunar mapping in the book’s preface. So you get to know both where this mapping data came from and where other data may be found.

In any case I suspect that you nor I will be going hiking on the Moon anytime soon. But perhaps you want to study lunar topography, lunar morphology or lunar geologic structures? Maybe you want to know where is the water that’s hiding on the Moon. I recommend “The Chang’E-1 Topographic Atlas of the Moon” by Chunlai Li, Jianjun Liu, Lingli Mu, Xin Ren and Wei Zuo. It may guide you to all sorts of interesting features and finds.

The book is available through Springer.

Posted on by Matt Williams

Moonbase by 2022 For $10 Billion, Says NASA

Based on a series of articles that were recently made available to the public, NASA predicts it could build a base on the Moon by 2022, and for cheaper than expected. Credit: NASA

Returning to the Moon has been the fevered dream of many scientists and astronauts. Ever since the Apollo Program culminated with the first astronauts setting foot on the Moon on July 20th, 1969, we have been looking for ways to go back to the Moon… and to stay there. In that time, multiple proposals have been drafted and considered. But in every case, these plans failed, despite the brave words and bold pledges made.

However, in a workshop that took place in August of 2014, representatives from NASA met with Harvard geneticist George Church, Peter Diamandis from the X Prize Foundation and other parties invested in space exploration to discuss low-cost options for returning to the Moon. The papers, which were recently made available in a special issue of New Space, describe how a settlement could be built on the Moon by 2022, and for the comparatively low cost of $10 billion.

Continue reading “Moonbase by 2022 For $10 Billion, Says NASA”

Posted on by David Dickinson

A Penumbral Lunar Eclipse Leads the Way to Easter Weekend

Chuck Manges
Can you see it? A penumbral eclipse from 2013. Image credit and copyright: Chuck Manges

Ready for Easter? The first of two lunar eclipses for 2016 occurs this week, though it’s an event so subtle, you might not notice it at first glance. We’re talking about Wednesday evening’s (morning for North America) penumbral lunar eclipse. If a total solar eclipse such as the one that crossed Indonesia and the Pacific Ocean earlier this month is the ultimate astronomical experience, then a penumbral lunar eclipse is at the other end of the spectrum, a ghostly shading on the Moon that is barely noticeable. Continue reading “A Penumbral Lunar Eclipse Leads the Way to Easter Weekend”

Posted on by Ken Kremer

NASA Test Fires SLS Flight Engine Destined to Launch Astronauts Back to the Moon

NASA engineers conduct a successful test firing of RS-25 rocket engine No. 2059 on the A-1 Test Stand at NASA’s Stennis Space Center in Bay St. Louis, Mississippi. The hot fire marks the first test of an RS-25 flight engine for NASA’s new Space Launch System vehicle. Credits: NASA/SSC
NASA engineers conduct a successfully test firing of RS-25 rocket engine No. 2059 on the A-1 Test Stand at NASA’s Stennis Space Center in Bay St. Louis, Mississippi. The hot fire marks the first test of an RS-25 flight engine for NASA’s new Space Launch System vehicle. Credits: NASA/SSC
NASA engineers conduct a successful test firing of RS-25 rocket engine No. 2059 on the A-1 Test Stand at NASA’s Stennis Space Center in Bay St. Louis, Mississippi. The hot fire marks the first test of an RS-25 flight engine for NASA’s new Space Launch System vehicle. Credits: NASA/SSC

NASA engineers have successfully test fired the first flight engine destined to power the agency’s mammoth new SLS rocket that will launch American astronauts back to the Moon and deep space for the first time in nearly five decades.

The flight proven RS-25 powerplant engine previously flew as one of three main engines that successfully rocketed NASA’s space shuttle orbiters to space during the three decade long Space Shuttle era that ended in 2011. Continue reading “NASA Test Fires SLS Flight Engine Destined to Launch Astronauts Back to the Moon”

Posted on by Evan Gough

First Tomatoes, Peas Harvested From Simulated Martian Soil

Researchers at Wageningen University in the Netherlands have harvested tomatoes and other vegetables grown in simulated Martian soil. Image: regan76 CC BY 2.0
Researchers at Wageningen University in the Netherlands have harvested tomatoes and other vegetables grown in simulated Martian soil. Credit: regan76 CC BY 2.0

We’re a long ways away from colonizing another planet—depending on who you talk to—but it’s not too soon to start understanding how we might do it when the time comes. Growing enough food will be one of the primary concerns for any future settlers of Mars. With that in mind, researchers at the Wageningen University and Research Centre in the Netherlands have created simulated Martian soil and used it to grow food crops.

This is actually the second experiment the team has performed with simulated soil, and the results were promising. The team harvested not only tomatoes and peas, but also rye, garden rocket, radish, and watercress. But it’s not just the edibles that were promising, it was the overall ability of the simulated soil to produce biomass in general.  According to the researchers, the soil produced biomass equal to that produced by Earth soil, which was used as a control.

The team also grew crops in simulated Moon soil, to understand how that soil performed, but it produced much less biomass, and only the humble spinach was able to grow in it. The simulated Martian and Lunar soils were provided by NASA. The Martian soil came from a Hawaiian volcano, and the Lunar soil came from a desert in Arizona.

The soil used was not exactly the same as the soil you would scoop up if you were on the Moon or Mars. It was amended with organic matter in the form of manure and fresh cut grass. While this may sound like a ‘cheat’, it’s no different than how gardens are grown on Earth, with gardeners using manure, compost, grass clippings, leaves, and even seaweed to provide organic matter.

Of course, none of these soil amendments will be available on the Moon or Mars, and we won’t be sending a supply ship full of manure. Colonists will have to make use of all of the inedible parts of their crops—and human feces—to provide the organic material necessary for plant growth. It’ll be a closed system, after all.

The crops were grown in a controlled environment, where temperature, humidity, and other factors were kept within Earthly parameters. Any crops grown on Mars will be grown in the same controlled environments, at least until genetic modification can create plants able to withstand the increased radiation and other factors.

A problem facing colonists trying to grow food on Mars is the heavy metal content of the soil. Mars soil contains mercury, lead, cadmium, and arsenic, which are all toxic to humans. The presence of these elements doesn’t bother the plants; they just keep growing. But any crops grown in this soil will have to be tested for toxicity before they can be consumed. This is the next experiment that the team has planned.

Researchers at the Wageningen University are currently crowdfunding for this next experiment. If you’d like to contribute, check out their page here.