Space and astronomy news
Shining like a beacon in Earth’s sky is the Moon. We’ve seen so much of it in our lifetimes that it’s easy to take it for granted; even the human landings on the Moon in the 1960s and 1970s were eventually taken for granted by the public.
Fortunately for science, we haven’t stopped looking at the Moon in the decades after Neil Armstrong took his first step. Here are a few things to consider about Earth’s closest big neighbor.
It’s all about timing and location.
You’ve probably seen images we’ve posted on Universe Today of planes crossing in front of the Sun or the Moon. But how do the photographers manage to capture these events? Hint: it’s not random luck.
“I live under a main flight path out of Heathrow,” said photographer Chris Lyons from the UK who took the image above earlier today, “and can easily spot the planes not long after they take off — if it is clear — from when they are about 100 miles away!”
Chris posts many of his images on Universe Today’s Flickr page, and what is great about Chris’ airplane photos is that he includes a handy infographic about the plane in the shot; the type of plane, its takeoff and destination, and more, garnered from online flight trackers.
Chris told Universe Today that he originally started trying to catch planes passing in front of the Moon.
“It went from snapping them near it when just taking Moon shots to wanting to get closer and have them actually passing it,” he said. “Then I got a Solar filter and tried it with the Sun. It is far more difficult than the Moon, as you cannot look at it for long. I limit my viewing (our eyes are precious) and only look through high rated neutral density filters.”
We’ve also featured images from Sebastien Lebrigand who lives about 70 km outside of Paris, France. Lebrigand is prolific: he takes almost daily images of planes passing in front of the Sun and Moon and posts them on Twitter.
Lebrigand is an amateur astronomer but says he especially enjoys “the rare conjunction of the planes passing by the Sun and the Moon.’
He uses a Canon EOS 60D and a telescope to take his photos the pictures. But his work takes hours of time for analyzing when a potential photo opportunity might occur, setting up equipment, waiting for the exact moment, and then perfecting the images.
Check out more of Chris Lyons’ work at his Flickr page, and you can see more of Sebastien Lebrigand’s work at his website or his Twitter feed.
The Full Moon celebrates Jupiter’s coming opposition by accompanying the bright planet in a beautiful conjunction tonight.
Even last night Jupiter and the Moon were close enough to attract attention. Tonight they’ll be even more striking. Two reasons for that. The Moon is full this evening and will have crept within 41/2° of the planet. They’ll rise together and roll together all night long.
February’s full moon is aptly named the Full Snow Moon as snowfall can be heavy this month. Just ask the folks in Chicago. The Cherokee Indians called it the “Bone Moon”, named for the tough times experienced by many Native Americans in mid-winter when food supplies ran low. With little left to eat people made use of everything including bones and bone marrow for soup.
Not only is the Full Moon directly opposite the Sun in the sky, rising around sunset and setting around sunrise, but in mid-winter they’re nearly on opposite ends of the celestial seesaw.
In early February the Sun is still near its lowest point in the sky (bottom of the seesaw) for the northern half of the globe. And while daylight is steadily increasing as the Sun moves northward, darkness still has the upper hand this month. Full Moons like tonight’s lie 180° opposite the Sun, placing the Moon near the top of the seesaw. Come early August, the Sun will occupy the Moon’s spot and the Full Moon will have slid down to the Sun’s current position. Yin and Yang folks.
Now here’s the interesting thing. Jupiter will also be in “full moon” phase when it reaches opposition this Friday Feb. 6. Take a look at the diagram. From our perspective on Earth, Jupiter and the Sun lie on opposite sides of our planet 180° apart. As the Sun sets Friday, Jupiter will rise in the east and remain visible all night until setting around sunrise exactly like a Full Moon.
So in a funny way, we have two Full Moons this week only one’s a planet.
Like me, a lot of you enjoy a good moonrise. That golden-orange globe, the crazy squished appearance at rising and the transition to the bright, white, beaming disk that throws enough light on a winter night to ski in the forest without a headlamp. All good reasons to be alive.
To find when the moon rises for your town, click over to this moonrise calculator. As you step outside tonight to get your required Moon and Jupiter-shine, consider the scene if we took neighboring Jupiter and placed it at the same distance as the Moon. A recent series of such scenes was released by the Russian Federal Space Agency (Roscosmos). I included one here and added the Moon for you to compare. Is Jupiter enormous or what?
Host: Fraser Cain (@fcain)
Guests:
Ramin Skibba (@raminskibba)
Dave Dickinson (@astroguyz / www.astroguyz.com)
Special Guest: Paul Hildebrandt from Fight For Space
Continue reading “Weekly Space Hangout – Jan. 30, 2015: Paul Hildebrandt Fights for Space!”
How would our horizon look if Earth orbited around another star, such as Alfa-Centauri, Sirius, or Polaris? Roscosmos TV has released two new videos that replace our familiar Sun and Moon with other stars and planets. While these are completely fantastical — as Earth would have evolved very differently or not evolved at all in orbit around a giant or binary star — the videos are very well done and they give a new appreciation for the accustomed and comforting views we have. The Sun video is above; the Moon below:
Check out Roscosmos TV You Tube page — they have a great collection of videos, from launches to science to fantastical videos like the ones we featured here.
What makes a planet a planet? The Moon is so big compared to the Earth — roughly one-quarter our planet’s size — that occasionally you will hear our system being referred to as a “double planet”. Is this correct?
And we all remember how quickly the definition of a planet changed in 2006 when more worlds similar to Pluto were discovered. So can the Moon stay the Moon, or is the definition subject to change?
Defining a planet
First, it’s important to understand what the official definition of a “planet” is, at least according to the International Astronomical Union. In its own words, according to a vote in Prague in 2006, the union has this definition:
“A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.”
What this means is that a planet must move around the Sun (and not move around something else), that it’s massive enough to have a round shape due to gravity, and that it will swoop up any dust or debris in its orbit as it moves around the Sun.
But let’s be clear on something; the IAU definition of planet is not without controversy. There is still a strong contingent of people who say that Pluto is indeed a planet, including the principal investigator of a spacecraft (New Horizons) to examine the world: Alan Stern.
“It’s an awful definition; it’s sloppy science and it would never pass peer review,” he told the BBC in 2006. He said that the line between dwarf planets and planets is too artificial, and that the definition of a “cleared neighborhood” is muddy. The Earth alone has many asteroids that follow it — or approach or cross its orbit — not to mention the massive planet Jupiter.
Definition of a ‘satellite’
The Moon is not a unique phenomenon in our Solar System, in the sense that there are other planets that have satellites around them. Jupiter and Saturn have many dozens! Referring again to the IAU, the union also said in 2006 that it does not consider Charon a dwarf planet despite its large relative size to Pluto.
But Charon’s status as a moon could change in future, the IAU acknowledged. That’s primarily because the center of gravity in the system is not inside of Pluto, but in “free space between Pluto and Charon”. This center is called the “barycenter”, technically — and in Jupiter and Saturn’s cases, for example, all the barycenters of the various moons reside “inside” the huge gas giants.
Another caution, however: the IAU says “there has been no official recognition that the location of the barycenter is involved with the definition of a satellite.” So for now, it doesn’t have any bearing. That said, one question to consider is if the Moon’s barycenter is inside the Earth?
The answer right now is “yes”. But over time, that barycenter will move outside of Earth. That’s because the Moon is slowly receding from our planet at a rate of about 3.8 centimeters (1.5 inches) a year. It’ll take a long time, but eventually the center of our system’s mass will not be within our planet.
And if you read back to an IAU interview in 2006, you’ll see that at that time, the IAU defined a “double planet” as a system where both bodies meet the definition of a planet, and the barycenter is not inside either one of the objects. So for now, the Earth is a planet and the Moon a satellite — at least under IAU rules.
We have written many articles about the Moon for Universe Today. Here’s an article about how long it takes to get to the Moon, and here are some interesting facts about the Moon. We’ve also recorded an entire episode of Astronomy Cast all about the Moon. Listen here, Episode 113: The Moon, Part 1.
Wonderful news! Asteroid 2004 BL86, which passed closest to Earth today at a distance of 750,000 miles (1.2 million km), has a companion moon. Scientists working with NASA’s 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, have released the first radar images of the asteroid which show the tiny object in orbit about the main body.
While these are the first images of it, the “signature” of the satellite was seen in light curve data reported earlier by Joseph Pollock (Appalachian State University, North Carolina) and Petr Prave (Ondrejov Observatory, Czech Republic) according to Lance Benner who works with the radar team at Goldstone.
2004 BL86 measures about 1,100 feet (325 meters) across while its moon is approximately 230 feet (70 meters) across. The asteroid made its closest approach today (Jan. 26th) at 10:19 a.m. (CST), however it will peak in brightness this evening around 10 p.m. (4:00 UT) at magnitude +9.0. Unlike some flybys, 2004 BL86 will remain within a few tenths of a magnitude of peak brightness from 6 p.m. tonight (CST) through early tomorrow morning, so don’t miss the chance to see it in your telescope.
Don’t expect to see the diminutive moon visually – the entire system will only appear as a point of light, but I’m sure you’ll agree it’s cool just knowing it’s there.
Among near-Earth asteroids, about 16% that are about 655 feet (200 meters) or larger are either binary or triple systems. While that’s not what you’d call common, it’s not unusual either. To date, we know of 240 asteroids with a single moon, 10 triple systems and the sextuple system of Pluto (I realize that’s stretching a bit, since Pluto’s a dwarf planet) – 268 companions total. 52 of those are near-Earth asteroids.
With a resolution of 13 feet (4-meters) per pixel we can at least see the roughness of the the main body’s surface and perhaps imagine craters there. No details are visible on the moon though it does appear elongated. I’m surprised how round the main body is given its small size. An object that tiny doesn’t normally have the gravity required to crush itself into a sphere. Yet another fascinating detail needing our attention.
Of course the main asteroid will get your attention tonight. Please check out our earlier story on 2004 BL86 which includes more details as well as charts to help you track it as it flies across Cancer the Crab tonight. This is the best view we’re going to get of it for the next two centuries.
I want to alert you to a rather unusual event occurring this evening.
Many of you already know about the triple shadow transit of Jupiter’s moons Io, Europa and Callisto. That’s scheduled for late tonight.
Earlier, around nightfall, the crescent moon will lie 1° or less to the south-southwest of comet 15P/Finlay. No doubt lunar glare will hamper the view some, but what a fun opportunity to use the moon to find a comet.
Finlay underwent a flare in brightness last week when it became easily visible in binoculars.
Though a crescent moon isn’t what you’d call a glare bomb, I can’t predict for certain whether you’ll still see the comet in binoculars tonight or need a small telescope instead. Most likely a scope. Finlay has faded some since its outburst and now glows around magnitude +8.5.
You can try with a 10×50 or larger glass, and if you don’t succeed, whip out your telescope; a 4.5-inch or larger instrument should handle the job.
Just point it at the moon at star-hop a little to the north-northeast using the map until you see a fuzzy spot with a brighter center. That’s your comet. The tail won’t be visible unless you’re using more firepower, something closer to 10-inches.
By the way, the father south you live, the closer the moon approaches Finlay. From the far southern U.S. they’ll be just 1/2° apart. Keep going south and parts of Central and South America will actually see the earth-lit edge of moon approach and then occult the comet from view!
UPDATE: Although light clouds marred the view I had difficulty finding the comet this evening in my 10-inch scope. It’s possible it’s further faded or my conditions weren’t optimal or both. No luck BTW in binoculars.
“By the Light of the Silvery Moon” goes the song. But the color and appearance of the Moon depends upon the particular set of eyes we use to see it. Human vision is restricted to a narrow slice of the electromagnetic spectrum called visible light.
With colors ranging from sumptuous violet to blazing red and everything in between, the diversity of the visible spectrum provides enough hues for any crayon color a child might imagine. But as expansive as the visual world’s palette is, it’s not nearly enough to please astronomers’ retinal appetites.
Since the discovery of infrared light by William Herschel in 1800 we’ve been unshuttering one electromagnetic window after another. We build telescopes, great parabolic dishes and other specialized instruments to extend the range of human sight. Not even the atmosphere gets in our way. It allows only visible light, a small amount of infrared and ultraviolet and selective slices of the radio spectrum to pass through to the ground. X-rays, gamma rays and much else is absorbed and completely invisible.
To peer into these rarified realms, we’ve lofting air balloons and then rockets and telescopes into orbit or simply dreamed up the appropriate instrument to detect them. Karl Jansky’s homebuilt radio telescope cupped the first radio waves from the Milky Way in the early 1930s; by the 1940s sounding rockets shot to the edge of space detected the high-frequency sizzle of X-rays. Each color of light, even the invisible “colors”, show us a new face on a familiar astronomical object or reveal things otherwise invisible to our eyes.
So what new things can we learn about the Moon with our contemporary color vision?
Radio: Made using NRAO’s 140-ft telescope in Green Bank, West Virginia. Blues and greens represent colder areas of the moon and reds are warmer regions. The left half of Moon was facing the Sun at the time of the observation. The sunlit Moon appear brighter than the shadowed portion because it radiates more heat (infrared light) and radio waves.
Submillimeter: Taken using the SCUBA camera on the James Clerk Maxwell Telescope in Hawaii. Submillimeter radiation lies between far infrared and microwaves. The Moon appears brighter on one side because it’s being heated by Sun in that direction. The glow comes from submillimeter light radiated by the Moon itself. No matter the phase in visual light, both the submillimeter and radio images always appear full because the Moon radiates at least some light at these wavelengths whether the Sun strikes it or not.
Mid-infrared: This image of the Full Moon was taken by the Spirit-III instrument on the Midcourse Space Experiment (MSX) at totality during a 1996 lunar eclipse. Once again, we see the Moon emitting light with the brightest areas the warmest and coolest regions darkest. Many craters look like bright dots speckling the lunar disk, but the most prominent is brilliant Tycho near the bottom. Research shows that young, rock-rich surfaces, such as recent impact craters, should heat up and glow more brightly in infrared than older, dust-covered regions and craters. Tycho is one of the Moon’s youngest craters with an age of just 109 million years.
Near-infrared: This color-coded picture was snapped just beyond the visible deep red by NASA’s Galileo spacecraft during its 1992 Earth-Moon flyby en route to Jupiter. It shows absorptions due to different minerals in the Moon’s crust. Blue areas indicate areas richer in iron-bearing silicate materials that contain the minerals pyroxene and olivine. Yellow indicates less absorption due to different mineral mixes.
Visible light: Unlike the other wavelengths we’ve explored so far, we see the Moon not by the light it radiates but by the light it reflects from the Sun.
The iron-rich composition of the lavas that formed the lunar “seas” give them a darker color compared to the ancient lunar highlands, which are composed mostly of a lighter volcanic rock called anorthosite.
Ultraviolet: Similar to the view in visible light but with a lower resolution. The brightest areas probably correspond to regions where the most recent resurfacing due to impacts has occurred. Once again, the bright rayed crater Tycho stands out in this regard. The photo was made with the Ultraviolet Imaging Telescope flown aboard the Space Shuttle Endeavour in March 1995.
X-ray: The Moon, being a relatively peaceful and inactive celestial body, emits very little x-ray light, a form of radiation normally associated with highly energetic and explosive phenomena like black holes. This image was made by the orbiting ROSAT Observatory on June 29, 1990 and shows a bright hemisphere lit by oxygen, magnesium, aluminum and silicon atoms fluorescing in x-rays emitted by the Sun. The speckled sky records the “noise” of distant background X-ray sources, while the dark half of the Moon has a hint of illumination from Earth’s outermost atmosphere or geocorona that envelops the ROSAT observatory.
Gamma rays: Perhaps the most amazing image of all. If you could see the sky in gamma rays the Moon would be far brighter than the Sun as this dazzling image attempts to show. It was taken by the Energetic Gamma Ray Experiment Telescope (EGRET). High-energy particles (mostly protons) from deep space called cosmic rays constantly bombard the Moon’s surface, stimulating the atoms in its crust to emit gamma rays. These create a unique high-energy form of “moonglow”.
Astronomy in the 21st century is like having a complete piano keyboard on which to play compared to barely an octave a century ago. The Moon is more fascinating than ever for it.
This has been on my bucket list for a while, but I’ve never had the opportunity to witness it myself: seeing the International Space Station transit the Moon. And now thanks to my friend Gadi Eidelheit, I want to see it for myself even more! He captured video and imagery of the ISS scooting in front of the Moon, from Ganot, Israel.
“This was just about 10km from my house!” Gadi told me via email. “I used a Canon 700d with Sigma 18-250 for the first clip and Canon sx50HS for the second clip (maximum zoom which equivalent to 1200mm). To find the best place I used Heavens-Above and a little trial and error! I just choose different locations near my home until I found the correct spot.”
For the first part of the video you need to look closely, as the transit happens quite quickly. But then Gadi slows it down, and later zooms in on the action. It still happens quite quickly but it’s very fun to see.
Gadi is an amateur astronomer and blogger who always has interesting things to post on social media or on his blog. You’ve really got me motivated now, Gadi!!