Tuesday, September 29, 2015

The Blood Moon Super Moon!

Flickr/ NASA's Marshall Space Flight Center

By Paola Salazar

Families and friends across the globe were watching the stars and sky Sunday night, whether cozily on porches and balconies, in the streets, at museums or at observatories, for a view they won't get for quite a while--the blood moon super moon! We dare you to say that five times fast.

But among our curios explorers at the Cambridge Science Festival, some may have been wondering--what exactly causes a blood moon, what makes this one a super moon or just generally, what is this big red thing in the sky where our "normal" moon should be?!

Fear not, for we are going to break it down for these curious minds right here, right now.

If we pretend this is an equation, the layout is like this:

Super Moon + Total Lunar Eclipse = Blood Moon Super Moon

But before we get into the nitty gritty details behind that, first we need a briefer on how the moon moves.

The moon and Earth both have elliptical orbits, meaning they move around in a not-quite circular fashion. The Earth revolves around our sun, while the moon completes a revolution around the Earth every 27 or so days.

Now, moving in an elliptical orbit also means that the moon and Earth don't have a set distance between each other. The average distance between the earth and the moon is 384,600 kilometers.

However, the distance varies at two points in particular--the apogee and the perigee. While not exactly the same, this is generally like the shape of an egg--one side is "taller," or further away (the apogee), while the end opposite that is closer to the center, or the "perigee."


The other thing is, the moon doesn't create its own light, it simply reflects the light that hits it from the sun. As the moon changes position around the earth, the side of the moon facing us reflects a different amount of sunlight as the light bounces off the surface of the moon--this is why every month, you can see a difference in what the moon looks like when it's waning, waxing, full and a new moon.

The amount of light and shade of color that we see from the moon depends not only on the postion of the moon, but on the type of rays that hit the moon. This is a form of "filtering" of colors that occurs because of the particles in our atmosphere at the time of night.

Every so often, the alignment of the sun, moon, and Earth, and the type of light that hits the moon during these alignments, result in some really neat tricks that can be visible to the naked eye (although sometimes, we need to wear protective sunglasses to see it).

For example (check out this video!)...

The Super Moon

source: DeviantArt | Nope, not that kind of Super Moon.
When the moon is in perigree, and the closest to Earth that it ever gets, we see it bigger and brighter than ever! The moon, at a distance of 363,700 km away, appears to be about 14% bigger from our perspective, and about 30% brighter. The size and brightness of it is what led to astronomers dubbing it the super moon!

When the moon is the furthest away from Earth, or in apogee, it's at about 405,600 km away and is the smallest that we can see it, appearing dimmer because of it. For these reasons, when the moon is in apogee, we refer to it as a minimoon.

Total Lunar Eclipse (AKA Why was the moon red?)
 A total lunar eclipse occurs every two and a half years when the Earth is aligned right between the moon and sun. While you might think that because the Earth is bigger than the moon, the moon should be entirely dark, the reason we don't see that happening is because the sun is, of course, even bigger than the Earth!

What that means is that when the moon is caught behind the full shadow of the Earth, the moon will still have some  reddish rays hit it as they get bent by the Earth's atmosphere, but only those reddish tones because of the "filtering" in our atmosphere, as mentioned above (read here for more). 

Or, rather, "You're basically seeing all of the sunrises and sunsets across the world all at once being reflected off the surface of the moon," as Dr. Sarah Noble, a program scientist at NASA, said with the New York Times.

The Blood Moon Super Moon

What made last night's viewing especially awesome for spectators is that while a total lunar eclipse and super moon occur pretty frequently, a super moon that coincides with a blood moon has not occurred since 1982--that's 33 years ago! The next one isn't expected for another 18 years too. That's quite a long time ago, and quite a while until we get to see this again! 

Seeing something this unique last night gets people across generations and continents to look back up at the stars with wonder, Dr. Noble suggested, resulting in the birth of the next generations of future astronomers.

Will you be among them?

NASA/Lauren Harnett/Wikimedia Commons

Food for Thought:
Ask your older family members if they remember seeing the blood moon super moon back in 1982--what were they doing when they saw it and who did they see it with?
What did you do to see the blood moon super moon last night?
The next one will be in 18 years. What do you think you'll be doing then? How do you think the world might be different 18 years from now? 

Paola is a Boston-based science journalist with a background in social and life sciences.

Friday, September 18, 2015

Homo naledi: A new Homo Species Shrouded in Mysteries

By Paola Salazar

Picture this: a woman covered head to toe in dirt and debris, her hair in a ponytail under a helmet, loose long clothing enveloping her lanky body, her hand reaching up to her cheek to wipe away sweat.
She’s wearing a helmet with a big bright flashlight attached to the front, and as she approaches a crack in the ground ahead of her, she switches the flashlight on. The fissure is about 7.5 inches wide, and is the entryway to a cave system that’s about 30 meters deep.

Robert Clark/National Geographic: Lee Berger’s daughter, part of the excavation team (left). Paola Salazar/Facebook/American Association of Physical Anthropologists: The FB announcement from Lee Berger (right).
This is one of the “underground astronauts” who flew to South Africa’s Cradle of Humankind when in 2013, paleoanthropologist Lee Berger announced the need for researchers who could fit into the cave entrance of what would then be known as the home of a newly discovered extant species related to modern humans, the Rising Star Cave. 

It’s through her and a team of five other female explorers that two years later, Berger was able to announce last Thursday that after two excavations, the results of their efforts was a whopping 1,550 hominid bones--hominid meaning humans and their fossil ancestors--and what’s more, that these fossils were attributed to at least 15 members of a new species, Homo naledi.

The researchers say that the species had a brain about the size of an orange, stood about 5 feet tall, and weighed about 100 lbs. They've also revealed more on its anatomy within their paper, published on the journal eLife.
Homo naledi/Witswatersrand University

But first of all, what exactly is a paleoanthropologist?

A paleoanthropologist is someone interested in studying, finding and/or analyzing modern human’s ancestors--human-like creatures known as hominids that, depending on how old they are, may still have some ape-like features.

Hominids come in two different genera, which is the general name for species or animals that are more closely related to each other than to other species--like how dogs are related to wolves and cats are related to wildcats under the same genera--Canis and Felis, respectively.

Depending on which anthropologist you ask, there are generally two genera for human ancestors: Australopithecus, for earlier and much older ancestors, and Homo, for the more recently extinct species and the current species, Homo sapiens. While paleoanthropologists have currently discovered numerous species related to humans, in each of the different species groups, they don’t have very many individual examples of each.

This is part of what makes the Rising Star Cave so unique--15 individuals were found! Not only that, but they found some that were children, some that were adults and even the elderly.

During the excavations back in late 2013 and early 2014, Berger and his research team shared much about the process of the excavation. They also provided an exciting day-by-day number count of the amount of bones being collected that started wowing interested parties across the globe from the very beginning (see the NatGeo blog here).

Most researchers will only release such information over time or with the actual publication itself, which can take years. However, Berger and his fellow researchers on the analysis and excavation teams strongly support open scientific communication with the public.

Still, he left one very important question unanswered: what was it? Was it a close relative to humans? Was it an australopithecine?

And now that Berger finally revealed the identity of Homo naledi...he then left many new questions for us to ponder!

So we at the Cambridge Science Festival tried getting some answers from one of the researchers, former Boston University professor, Jeremy DeSilva, who is now an associate professor at Dartmouth College in New Hampshire.

One of the new bits of mind-boggling information we got from Berger was the suggestion that the cave itself, being so far deep into a larger cave system (see here) was actually being used as a burial site by Homo naledi during its time as a living species.
    National Geographic: The fossils were found in the Dinaledi Chamber--look how far down that is!

National Geographic

DeSilva explained that while this idea was the first of its kind for species this old (since most signs of purposefully burying the dead are about 100,000 years ago), it was the only one they could seem to fit with the evidence they have so far.

“The thing is, with cave sites, we can usually tell what the caves are used for. For example, if there are signs of bite marks on the bones found and if we find bones of other animals that are not hominids, then we know it was likely a dump site for predators. Here, we really only found Homo naledi--that’s it.” Any animal bones found were higher up within the cave system.

He also said that there was sedimentation between each different fossil group that they found, meaning that after revealing one set of bones, the next set of bones would be another layer or two of digging below.

To top it off, there’s also ways of telling if the bones got there by natural causes like landslides, or perhaps rain carried sediment further down the cave system, and the bones traveled with it. Again, there was no sign of this on the site!

Another odd thing about the site was that they weren’t able to date when Homo naledi was actually walking around on land, which is information that’s highly important for researchers trying to figure out the significance of the discovery.This is again because of the fact that Homo naledi was found by itself, or isolated, from other signs of life during its time.

See, having the bones of other animals would mean that the researchers could analyze those bones as well, trace where and when in time that animal was alive, and be able to tell from there when Homo naledi was alive.

But because there were no animals found with the Homo naledi fossils, and because cave dirt and mud is very hard to analyze for dating purposes as well, the researchers won’t be able to date Homo naledi until they’re done analyzing its bones and can “sacrifice” one to someone on the team who can analyze the bone directly to date it.

“When this guy was walking around makes a big difference,” DeSilva said. “If it was older than 2 million years old, then it could be the earliest member of the Homo genus; if it’s around 2 million years old then it’s adding to the collection of cousins to modern humans; and if it’s younger than 1 million years old then that’s huge, because it could mean that earlier versions of modern humans weren’t the only ones walking around at the time,” DeSilva explained, since right now, that is what human evolutionary history suggests.

Still, DeSilva said that going by its anatomy, he does not think Homo naledi would be younger than 1 million years old--though he admits he’d be excited if it was.

Aside from the significance of when exactly they were alive, something else that’s intriguing about Homo naledi is that whenever it is that they were walking around, they actually walked around with features that were still somewhat primitive (more ape-like), which is odd for something that has so many human-like features.

For example, their shoulders and slightly more curved fingers suggest that they were still much better at climbing than we are now. Were they climbing in trees or through caves? Was it for shelter or to escape predators?

That’s also unknown, unfortunately, according to DeSilva, who specializes in the functional morphology (how and why bones look the way they do) of foot bones and the lower limbs. He said there aren’t enough studies on the biomechanics of cave or rock climbers--meaning we don’t fully understand the range of motion that cave/rock climbers use, or what kind of forces they exert on their bones, or how those forces affect the shape and density of their bones after years of climbing in that way.

DeSilva said that while the big reveal has just happened now, they’ve already spent the last year focusing on more detailed analyses related to how Homo naledi lived: how it walked (this is what he and a few others are working on), what it ate, trying to see if they can recover any DNA, and more.

While they work towards better defining Homo naledi, the release has brought criticism from other researchers as well, due to disagreement on whether or not Homo naledi is actually a new species or an addition of specimen for an already known early Homo species.

The research team welcomes the criticism though, and has even made the fossils available online (link at the bottom) to anyone wanting to see the fossils out of curiosity or out of the desire to find evidence for whatever is believed to be incorrect in their conclusions. They did this because in addition to their open-access mentalities, they realize that some of the conclusions they made after careful consideration of what was discovered are hard to wrap our heads around--burials, new species, its features, dating, etc.

“There’s no doubt that this is a significant find,” DeSilva said. “But without the date, we can’t fully tell just how significant it is.”

“It absolutely questions what makes us human,” Lee Berger said in an interview for CNN, “And I don’t think we know anymore.”

Berger, his fellow researchers, and South African leaders and government officials suggest that one of the more important aspects about the discovery is that it introduces or reignites people’s interest in human origins, field work, and science in general across generations.

Speaking to a group of high schoolers for the World Science Festival, Berger said younger generations are crucial to making even more discoveries not just in technology, but out in the open.

“We need [these] generation[s] to get out from behind those computers and start exploring,” Berger said, “Even areas where we think we know what’s there, because there are still things to be discovered.”

Want to see the actual bones? Click here!
For more on Homo naledi, the researchers, and the excavation, click here!
Want to see and read more on how hominids move? Catch more info from Prof. DeSilva here!

Paola is a Boston-based science journalist with a background in social and life sciences.

Thursday, September 10, 2015

More on the Brain: How Do Our Brains Control Our Bodies?

By Paola Salazar

[“El Jaleo” by John Singer Sargent, Isabella Stewart Gardner Museum, Boston, MA.]

12-year-old Amanda Kelly asks how it is that one organ (the brain) can control an entire body’s functions and motions. Again, the MIT student group Communicating Science provided an answer for us.

The brain is made up of a vast number of special communication cells called neurons that carry signals around the body. The brain has a sort of special highway of neurons that carry instructions directly to your spine. This is the spinal cord, where motor (for motion) and sensory (for feeling) nerves branch out.

From the spinal cord, the motor signals are sent out to your muscles, where they release tiny signal molecules called neurotransmitters. These neurotransmitters cause your muscles to contract, leading to motion. 

We don't really understand how the spinal cord knows which signals to send to which muscles, though - these kinds of questions remain open for the next generation of scientists, like yourself!

For anyone wanting to read more on what we know about how the brain controls movement, click here

Paola is a Boston-based science journalist with a background in social and life sciences.