Starsglaxiesspace - SPACE

The Moon in Motion

Happy New Year! And happy supermoon! Tonight, the Moon will appear extra big and bright to welcome us into 2018 – about 6% bigger and 14% brighter than the average full Moon. And how do we know that? Well, each fall, our science visualizer Ernie Wright uses data from the Lunar Reconnaissance Orbiter (LRO) to render over a quarter of a million images of the Moon. He combines these images into an interactive visualization, Moon Phase and Libration, which depicts the Moon at every day and hour for the coming year. 

Want to see what the Moon will look like on your birthday this year? Just put in the date, and even the hour (in Universal Time) you were born to see your birthday Moon.

Our Moon is quite dynamic. In addition to Moon phases, our Moon appears to get bigger and smaller throughout the year, and it wobbles! Or at least it looks that way to us on Earth. This wobbling is called libration, from the Latin for ‘balance scale’ (libra). Wright relies on LRO maps of the Moon and NASA orbit calculations to create the most accurate depiction of the 6 ways our Moon moves from our perspective.

1. Phases

The Moon phases we see on Earth are caused by the changing positions of the Earth and Moon relative to the Sun. The Sun always illuminates half of the Moon, but we see changing shapes as the Moon revolves around the Earth. Wright uses a software library called SPICE to calculate the position and orientation of the Moon and Earth at every moment of the year. With his visualization, you can input any day and time of the year and see what the Moon will look like!

2. Shape of the Moon

Check out that crater detail! The Moon is not a smooth sphere. It’s covered in mountains and valleys and thanks to LRO, we know the shape of the Moon better than any other celestial body in the universe. To get the most accurate depiction possible of where the sunlight falls on the lunar surface throughout the month, Wright uses the same graphics software used by Hollywood design studios, including Pixar, and a method called ‘raytracing’ to calculate the intricate patterns of light and shadow on the Moon’s surface, and he checks the accuracy of his renders against photographs of the Moon he takes through his own telescope.

3. Apparent Size 

The Moon Phase and Libration visualization shows you the apparent size of the Moon. The Moon’s orbit is elliptical, instead of circular - so sometimes it is closer to the Earth and sometimes it is farther. You’ve probably heard the term “supermoon.” This describes a full Moon at or near perigee (the point when the Moon is closest to the Earth in its orbit). A supermoon can appear up to 14% bigger and brighter than a full Moon at apogee (the point when the Moon is farthest from the Earth in its orbit). 

Our supermoon tonight is a full Moon very close to perigee, and will appear to be about 14% bigger than the July 27 full Moon, the smallest full Moon of 2018, occurring at apogee. Input those dates into the Moon Phase and Libration visualization to see this difference in apparent size!

4. East-West Libration

Over a month, the Moon appears to nod, twist, and roll. The east-west motion, called ‘libration in longitude’, is another effect of the Moon’s elliptical orbital path. As the Moon travels around the Earth, it goes faster or slower, depending on how close it is to the Earth. When the Moon gets close to the Earth, it speeds up thanks to an additional pull from Earth’s gravity. Then it slows down, when it’s farther from the Earth. While this speed in orbital motion changes, the rotational speed of the Moon stays constant. 

This means that when the Moon moves faster around the Earth, the Moon itself doesn’t rotate quite enough to keep the same exact side facing us and we get to see a little more of the eastern side of the Moon. When the Moon moves more slowly around the Earth, its rotation gets a little ahead, and we see a bit more of its western side.

5. North-South Libration

The Moon also appears to nod, as if it were saying “yes,” a motion called ‘libration in latitude’. This is caused by the 5 degree tilt of the Moon’s orbit around the Earth. Sometimes the Moon is above the Earth’s northern hemisphere and sometimes it’s below the Earth’s southern hemisphere, and this lets us occasionally see slightly more of the northern or southern hemispheres of the Moon! 

6. Axis Angle

Finally, the Moon appears to tilt back and forth like a metronome. The tilt of the Moon’s orbit contributes to this, but it’s mostly because of the 23.5 degree tilt of our own observing platform, the Earth. Imagine standing sideways on a ramp. Look left, and the ramp slopes up. Look right and the ramp slopes down. 

Now look in front of you. The horizon will look higher on the right, lower on the left (try this by tilting your head left). But if you turn around, the horizon appears to tilt the opposite way (tilt your head to the right). The tilted platform of the Earth works the same way as we watch the Moon. Every two weeks we have to look in the opposite direction to see the Moon, and the ground beneath our feet is then tilted the opposite way as well.

So put this all together, and you get this:

Beautiful isn’t it? See if you can notice these phenomena when you observe the Moon. And keep coming back all year to check on the Moon’s changing appearance and help plan your observing sessions.

Follow @NASAMoon on Twitter to keep up with the latest lunar updates. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Hey!! I find marine biology super cool, but everyone tells me I won't get a stable salary from it. Any advice?

Hello!! So sorry about the late reply. Anyway, I understand your struggle with people constantly wondering about the financial stability of a scientific career. For some scientific careers, especially those relating to marine biology, it is hard to estimate earnings because there are so many different pathways to chose from. What I mean by this is that your could take your passion for the ocean and work in many different places doing vastly different things. For example, you could work at a university teaching students and researching, or you could work in an aquarium taking care of animals, or you could work at a private research company/consulting firm. Each of these paths have different salary ranges. Another thing about marine biology is that it is a highly competitive field (and may be one of the reasons why people see this career as less stable than others.) 

I will not lie to you and say that marine biology careers are the most lucrative option out there; however, this does not mean that you cannot make a stable salary! Marine science careers, in my opinion, are more about your passion and drive to discover, educate, or conserve. So my main advice would be to continue doing what you love. If you are passionate about marine biology you will find that the advantages far outweigh the few downfalls. Also if you are not quiet sure if a career in marine sciences is your calling then you still have plenty of time to figure it out. Try interning or volunteering where you may be able to earn some experience.

Sorry about my rambling!! I hope it helped at least. 

And if it didn’t I highly suggest you check out SciAll.org’s YouTube channel. He has some cool videos. The video I linked here may help to answer your question.

Thank you so much and have a Thresher Shark for the road!!

Night Sky & Ursa Major

“Most Distant Supermassive Black Hole Discovered”

 An international group of astronomers have discovered and measured the most distant supermassive black hole to date.  This newly-discovered black holes sit in the centre of an ultrabirght quasar that was emitted just 690 million years after the Big Bang. The remarkable thing is that this light has taken almost 13 billion years to reach us - almost the same age as the Universe.  The discovery, which was made possible through data collected by the DECam Legaxy Survey (DECaLS) at the CTIO Blanco telescope, has shown that the black hole has a mass of approximately 800 million solar masses - humongous for today’s standards. This has lead to some astronomers theorizing that the very early Universe might have had ripe conditions allowing the creation of very large black holes, such as those with masses reaching 100,000 times the mass of the Sun.  “Gathering all this mass in fewer than 690 million years is an enormous challenge for theories of supermassive black hole growth,” said team leader Dr. Eduardo Bañados, from Carnegie Observatories.

Read more about this fascinating story at: http://www.sci-news.com/astronomy/most-distant-supermassive-black-hole-05509.html

Image: Artist’s conception of the most-distance supermassive black hole every discovered via Robin Dienel / Carnegie Institution for Science