Archive for the ‘AstroInfo Article’ Category
Worlds of Stone: 10/19/2011
As part of the current show (Worlds of Stone) at Pacific Science Center we’re updating the images we show from NASA’s MESSENGER and Dawn missions on a weekly basis. I’ll try to show them to you the week after we use the in the planetarium.
Dawn
- CGI Image of a Mountain on Vesta Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI
NASA Caption
Released October 11, 2011
PASADENA, Calif. — A new image from NASA’s Dawn spacecraft shows a mountain three times as high as Mt. Everest, amidst the topography in the south polar region of the giant asteroid Vesta.
The peak of Vesta’s south pole mountain, seen in the center of the image, rises about 13 miles (22 kilometers) above the average height of the surrounding terrain
Another impressive structure is a large scarp, a cliff with a steep slope, on the right side of this image. The scarp bounds part of the south polar depression, and the Dawn team’s scientists believe features around its base are probably the result of landslides.
This image was created from a shape model of Vesta, and shows an oblique perspective view of the topography of the south polar region. The image resolution is about 300 meters per pixel, and the vertical scale is 1.5 times that of the horizontal scale.
Alice Says
NASA’s caption is pretty clear, most important is to note that THIS IS A CGI IMAGE, and it is vertically exaggerated 1.5 times. This mountain is measured from the average height of the ground around it.
MESSENGER
Lava Flow on Mercury Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
NASA Caption
Date acquired: April 20-22, 2011
Release Date: October 17, 2011
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Of Interest: This mosaic shows the geological contact between a lava flow front, which advanced from the west (left) and the pre-existing terrain that it covered. The lava flowed into and almost completely filled a medium-sized crater in the center of the scene. Other amazing lava flow features were shown in recent Gallery releases.
Alice Says
NASA’s caption says you can see an ancient, solidified lava flow here, and you can see how it covers the land behind it. The front is just like the crest of a water wave – only this was a wave in rock and it froze in place as the lava solidified.
It is a little hard to tell which is the lava flow front here – the line that runs vertically through the image, or the one that runs horizontally. They cross exactly in the middle of the image. NASA’s caption is talking about the vertical line. You can see the crater they’re talking about – you can only see the top right-hand quarter of the rim of the crater, just above where the two lines cross.
Want More?
Worlds of Stone at Pacific Science Center
~ A l i c e !
Worlds of Stone, Worlds Unknown: NASA Investigates Mercury and the Asteroid Belt
We opened a new show in the Willard Smith Planetarium at Pacific Science Center. It’s all about NASA’s current missions in the inner solar system: MESSENGER to Mercury and Dawn to Vesta and Ceres.
As part of that show we’re updating the images we show from MESSENGER and Dawn on a weekly basis. I’ll try to show them to you the week after we use the in the planetarium.
Dawn
Boulders on Vesta Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
NASA Caption
Released October 12, 2011
PASADENA, Calif. — This detail of a Dawn FC (framing camera) image shows a fresh scarp rimmed crater with many boulders on the crater floor. These boulders have diameters of 100-200m, which is roughly the size of many asteroids! Also evident in this image are linear mass movement features, which originate from the rim of the crater (bottom of image) and are due to material slumping towards the center of the crater. There are also many smaller, and presumably younger, impact craters on the walls of this crater.
NASA’s Dawn spacecraft obtained this image with its framing camera on September 20th 2011.
Alice Says
Let me unpack what NASA said for you:
- “Fresh scarp rimmed crater “ – This crater is new, and it has a sharp edge, like a cliff (a scarp).
- “Boulders on the crater floor. These boulders have diameters of 100-200m,” – That’s those tiny black dots in the middle there.
- “Linear mass movement features” – Dirt moved. It moved in a straight line. The lines you see that go from the edge of the crater in towards the middle are these “linear features.” And technically I shouldn’t call it dirt. Regolith is better, but dirt gives you the right idea.
- “Due to material slumping towards the center of the crater.” – slumping is like sliding. Imagine yourself sitting against a wall. You sit straight at first and then get tired so you scootch down a little, and maybe lean over on your elbow. Slumping is dirt doing the same thing, it’s just … slumped. It’s different that sliding because when you slide you end up all in a completely different place. Slumping you just compact in place, maybe spreading out a little at the bottom.
- “Presumably younger” – when one crater is on top of another you can assume the crater on top is younger.
The boulders (dots) are my favorite part of this image.
MESSENGER
Mercury in Limb-O Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
NASA Caption
Date acquired: September 19, 2011
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Of Interest: This image provides us with a beautiful view of a portion of Mercury’s southern hemisphere. The bright rayed crater near the limb is Debussy.. Also visible, near the center of the image, is Matabei, a small crater distinguishable by its unique dark rays.
These limb images provide information about Mercury’s shape.
Alice Says
I love bright craters – they’re bright because they’re new, not because their composition is different. So rocks are made of minerals, and minerals are usually crystals: they have a lattice of atoms very perfectly aligned. If you just leave a crystal out on a planet it gets scratched up, banged around and the surface gets marred or weathered. If you crack that crystal open, it cracks (cleaves) along those perfect lattice boundaries, between atoms, exposing a new surface. This surface is perfectly flat –flat at the molecular level!! – and therefore reflective like a mirror. This is a cleavage plane. When you smack a meteorite into a planet, you kick up a bunch of rocks and minerals, cracking them all open along those cleavage planes. These fall back down to the planet, reflective, pretty, and unmarred – which looks from space like a bright white crater and rays.
Want More?
Worlds of Stone at Pacific Science Center
~ A l i c e !
My Star Exploded Last Week
My star¹ exploded² sometime in the week preceding last Monday³.
Let me repeat that because it is awesome.
MY STAR EXPLODED LAST WEEK!!!!!!!!!!!
¹My star: back in the summer of 2000 I had the fortune to be working as an undergraduate peon researcher in an astrophysics lab at MIT. In my seemingly endless hours sifting through data I found a previously-unidentified star (technically “source”) which we creatively named XTEJ1837+037. I have ever since referred to this as “my star” assuming it was such a pointless little dot that no one would care if I claimed the credit or not. It’s pretty close to Vega, and might be a binary system – a star orbiting a black hole or neutron star. It is perhaps more accurate to say “there was an explosion at my star.”
²Exploded: I’m being very loose with the definition of “exploded” here. NASA’s SWIFT Telescope detected an outburst near the coordinates of “my star.” This does not mean my star exploded, but something did something at that location. If it is a binary system then this outburst could easily be material from the regular star falling onto the black hole/neutron star companion.
³Sometime in the week preceding last Monday: SWIFT detected the burst between September 25, 2011 and October 15, 2011. Well, that means the light got to Earth two weeks ago – but as to when the burst actually happened? To know that we’d have to know how far away “my star” is.
Basic Stats
Source: an unidentified x-ray source, probably a binary system of a star and a neutron star and a black hole.
Name: XTEJ1837+037 or SWIFTJ1836.6+0341
Satellite used: first XTE, the X-Ray Timing Explorer, now SWIFT from NASA
What happened: a burst in the same area was detected using the burst-detecting instrument onboard SWIFT.
When: the detection occurred between September 25 and October 15, 2011.
Where in the sky: near Vega.
Where in the galaxy/universe: we don’t know. It could be in the galaxy, or it could be farther. It is probably in our galaxy, likely at least one kiloparsec away (far).
More Details and More Story
My Unidentified X-Ray Source
Source just means there’s a point in the sky that photons are coming from. The Sun is an identified and named source of visible light, radio waves, x-rays … etc. I was working under Ron Remillard at MIT at the time we found this source, and I was searching through data from the X-Ray Timing Explorer (XTE) to see if I could find gamma ray bursts for his research. I call it a star above because it was not an outburst like we were looking for, this object was steady – not something that shone brightly and then disappeared. The quickest and easiest name for that is “star.” It is important to note that we were using an x-ray telescope to do this research. This star was not visible – it shone only in x-rays, and it was very dim which is why it had not been found before.
I still asked Ron what constellation it was in. To me, even though the star wasn’t visible, being able to look towards it or point towards it was important. I don’t think Ron understood why. I know it isn’t visible. I also know it is there. It’s by Vega, at right ascension 18 degrees 37 minutes and declination +37 degrees.
We even got to name it. Ron explained how this would work. We named it XTEJ 1837+037, there was no discussion or debate, the name is formulaic. XTE is the name of the satellite used. J is there to let you know what years the coordinates are good for. In this case the coordinates are good during epoch J (12:00 Universal Time on January 1, 2000). 1837+037 are the coordinates: right ascension and declination (which can be positive or negative).
It is still an “unidentified source” because we didn’t take the time to figure out what it was. It wasn’t what we were looking for. Dr. Hans Krimm who recently rediscovered it with SWIFT speculates that it is probably a binary system – a regular star orbiting a black hole or neutron star. That would explain the recent outburst.
An Outburst
As I said, we actually have no idea what happened yet, and I am no longer involved in this research. NASA’s SWIFT telescope detected an outburst in that same area. In Hans’s words – SWIFT detected an outburst only 1.3 arc minutes from “my star.” That means it is very likely it is the same source.
With a binary system including a regular star and a black hole or neutron star, material can fall off the star and into the black hole or onto the neutron star. This is a catastrophic event, although not destructive to the binary system, and can easily create a large outburst. In fact, it is one of the types of supernovae. (Oops, I was confused. Type 1a supernovae are caused by mass falling from a star in a binary system onto a white dwarf not a neutron star or black hole. It can still create an outburst though.)
Stay tuned, I’ll be keeping up to date on this research. I hope you’re excited too!
Want More?
This is where it gets intense. The only links I have to point out to you are very, very technical. It took me three tries to read the first sentence of the first one … which could have something to do with how excited I was. Have fun deciphering!
The Astronomers Telegram and the second one.
Here are some more tractable links about the spacecraft in question:
~ A l i c e !
Neutrinos Faster than Light?
The scientists running the OPERA detector in Italy detected some neutrinos from CERN 60 nanoseconds before photons travelling the same distance would have arrived. Hmm. Such data would indicate that the neutrinos are travelling faster than light. Hmm. Extraordinary claims require extraordinary evidence. These scientists are asking other scientists in the field to find the mistake in their research – so that’s ongoing.
Is This New?
We’ve seen this before. Neutrinos do not interact with anything (pretty much) – they sail through solid rock like it is empty space. Photons do interact, that’s why you can see. Imagine a race between two particle-people “N” and “P.” First, let’s have them both in empty space. They race from the Sun to the Earth (zoom!) and P wins by a bit. So we know P is faster. Now, let’s give P a handicap. P is going to race by swimming through molasses, while N still gets to run the race in empty space. Now who wins? Well, in this case N does, because he’s not hampered by the molasses. It is just like that with photons, they’re slowed down as they interact with matter – the Sun, the Earth, the solar wind, whatever is out there. The neutrinos just zip right through. So neutrinos from the middle of the Sun get to the Earth long before photons from the middle of the Sun – the photons have to get through all that Sun-material first. Neutrinos and photons from the surface of the Sun would arrive at Earth at about the same time though, because it’s mostly just space in between.
Three Ideas
Three ideas about these FTL (faster than light) neutrinos:
1) They’re not faster than light, they’re just not interacting and the light is. This idea is simplistic and too easy for the scientists not to have ruled it out already.
2) Measurement error. As per the Bad Astronomer, these scientists need to measure the distance to within 3 meters exactly. Is that possible? Maybe. If they’re off by more than 3 meters, those 60 nanoseconds are probably just error.
3) The speed of neutrinos is pretty darn close to the speed of light, maybe our measurements before weren’t sensitive enough to pick up that the speed limit of the universe is the speed of neutrinos, not the speed of light. Now we have to go rewrite all of science fiction in addition to all of physics. What a pain.
Pretty much everyone is unconvinced, but no one has come up with a problem in the scientific evidence yet.
Want More?
The Actual Paper (you are unlikely to want to read this)
~ A l i c e !
UARS Re-entry
NASA’s UARS (Upper Atmosphere Research Satellite) re-entered the Earth’s atmosphere last night between 8:20pm and 10:10pm Pacific Time. At the time of this writing (2am? Oops), the exact time and location of re-entry are unknown, though NASA says it was over the Pacific Ocean. There were some unconfirmed reports that it fell over northern Canada.
More Interesting
What I found most fascinating is why they were unable to predict the exact decay of this orbit: solar radiation. Solar radiation (think heat from the Sun, though it would be more precise to say photons from the Sun) heats up the Earth’s atmosphere, specifically the upper atmosphere where satellites in Low-Earth Orbit can be as their orbits decay. This heating makes that part of the Earth’s atmosphere both larger and less dense. NASA likens this to a marshmallow being toasted over a campfire. So now your satellite is travelling through a different density of atmosphere, where it will experience more or less drag depending on what exactly is happening between the Sun and the Earth’s upper atmosphere. Complicated, especially if you can’t see that density changing.
Want More?
NASA’s UARS site with the most recent official updates
More about solar radiation and satellite orbit decay
Twitter and Spaceflight Now have more information, but not official information
~ A l i c e !
Autumn Equinox Sunset Watch 2011
Time for the seasonal sunset watch. I hope you’re excited, we had such fun at the last-minute stargazing last week.
- When: September 23, 2011 at 6:50pm (so come at 6:30pm)
- Actual sunset is supposed to be at 7:05, but at the summer solstice we noticed that the Sun set about 10 minutes earlier than the USNO says it does, so I’ve moved the time of our sunset watch up so we don’t miss it. I added another 5 minutes for the tall trees of Lincoln Park blocking our view.
- Where: Solstice Park – all the way up the hill from the tennis courts (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
- Who: Everyone welcome, as usual.
Sunset on June 21, 2011 at 9pm Credit: Jason Gift Enevoldsen
Today is a great day to announce the Autumn Equinox Sunset Watch because today is the Zhōngqiū Jié, 中秋節, or the Mid-Autumn Festival! Legend has it that once upon a time there were ten Suns, but Hou Yi was very strong and shot nine of them out of the sky. He was rewarded with the Elixir of Life – which would make him immortal. Unfortunately, he was so full of himself that he became a lazy tyrant, and his wife Cháng’é didn’t think it was a good idea for him to live forever, so she took the Elixir instead and began to float away. If you want to find out what happened to Cháng’é, you’ll have to come to the Sunset Watch where I will tell the whole story!
Today would be a great day to visit the Seattle Chinese Garden, here in West Seattle!
Come watch the autumn equinox sunset at Solstice Park in West Seattle on Friday the 23rd. We’ll see if the sunset lines up with the placed marker (it did for summer, but will it for fall?). I’ll be there even if it is cloudy because sometimes the Sun peeks through just as it begins to set, but if it is driving rain I’m staying home.
If you’re interested – here’s the timing of various celestial events on Saturday from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:
Sun and Moon Data for One Day
The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):Friday 23 September 2011 Pacific Daylight Time
SUN
Begin civil twilight 6:26 a.m.
Sunrise 6:57 a.m.
Sun transit 1:02 p.m.
Sunset 7:05 p.m.
End civil twilight 7:36 p.m.MOON
Moonset 4:22 p.m. on preceding day
Moonrise 2:13 a.m.
Moon transit 9:40 a.m.
Moonset 4:53 p.m.
Moonrise 3:30 a.m. on following dayPhase of the Moon on 23 September: waning crescent with 18% of the Moon’s visible disk illuminated.
Last quarter Moon on 20 September 2011 at 6:39 a.m. Pacific Daylight Time.
This event is my part of the NASA’s Solar System Ambassadors program, and thanks to West Seattle Blog for publicizing the last few!
Everyone is welcome, see you there!
Resources on Zhōngqiū Jié: Childbook, Chinatown Online, and Wikipedia.
~ A l i c e !
Last-Minute Stargazing – Comet Garradd and Supernova PTF11kly in Galaxy M101
The weather looks reasonable, so let’s try for some guerrilla stargazing at Solstice park tonight.
- When: TODAY! Sept 4, 2011 at 9pm
- Where: Solstice Park – all the way up the hill from the tennis courts (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
- Who: Everyone welcome, as usual.
- Sunset at Solstice Park on June 21, 2011 at 9pm
Credit: Jason Gift Enevoldsen
Come stargaze with us at Solstice park tonight. We’ll be looking for Comet Garradd and Supernova PTF11kly in Galaxy M101 through telescopes.
Here’s approximately what those might look like with out telescopes. They will not be visible to the naked eye.
Comet Garradd
- A collection of images of Comet Garradd from August 20, 2011 by Flickr user 37 Hz.
Supernova PTF11kly in Galaxy M101
- All rights reserved by David W. Bishop
If you’re interested – here’s the timing of various celestial events for today from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:
Sun and Moon Data for One Day
The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):
Sunday 4 September 2011 Pacific Daylight Time SUN Begin civil twilight 6:00 a.m. Sunrise 6:32 a.m. Sun transit 1:08 p.m. Sunset 7:44 p.m. End civil twilight 8:16 p.m. End astronomical twilight 9:34 p.m.MOON Moonset 10:40 p.m. on preceding day Moonrise 2:58 p.m. Moon transit 7:16 p.m. Moonset 11:34 p.m. Moonrise 3:53 p.m. on following day
This event is my part of the NASA’s Solar System Ambassadors program, and thanks toWest Seattle Blog for publicizing the last few!
Everyone is welcome, see you there!
~ A l i c e !
Live Commentary – Last Shuttle Launch
Are you reading this in a pre-coffee haze? Click on this link:
Alice’s Live Shuttle Launch Comments
Here’s what’s happening, if you’re not in the haze of the uncaffinated early morning:
Provided the weather in Florida holds out, I’ll be commenting live about the final shuttle launch tomorrow morning around 7:30/7:45am Seattle time (PDT). I am still here in Seattle, but since the launch is scheduled for 8:26am our time and Pacific Science Center won’t be open yet, I thought we could chat online.
Joining me will be Sarah Culp, planetarium intern, and Ballard High School graduate (class of ’11!). She and her class sent an experiment with e-coli up on the previous shuttle mission. We’ll probably chat about that as well.
If you want to join us, we’ll be on Twitter (AlicesAstroInfo) using the hashtag #PacSciLive, as well as the official launch hashtag #STS135. You don’t have to sign in to Twitter to read the comments, but you do if you want to talk back. You can also leave comments below, on my Facebook page or e-mail me. I’ll be watching all those for questions from you.
Cross your fingers for good weather in Florida!
~ A l i c e !
Rare Lunar Eclipse – June 15, 2011
There is an eclipse on Wednesday June 15, being touted as a rare central lunar eclipse. It is – but it is also very similar to the eclipse we had in December. The “rare” part is that it has a whopping 1 hour and 40 minutes of totality (that’s when the whole face of the moon is darkened by the Earth’s shadow). The eclipse we saw in December had 1 hour and 12 minutes of totality.
Unfortunately, the eclipse is not visible here at all – it peaks at 2:15 in the afternoon, and on Wednesday the Moon will not be visible from Seattle at that time. There is an observatory in Israel that will hook up a live feed to the internet if you want to watch on the web.
Lunar Eclipse 12/21/2010 in Seattle ©2010 Jason Gift Enevoldsen
Most lunar eclipses I’ve seen have had much shorter periods of totality – though it looks like more than an hour is not uncommon. Between the year 2000 and the year 2020, periods of totality last as little as 5 minutes and up to an hour and a half. Usually they seem to be about an hour.
Want More?
http://eclipse.gsfc.nasa.gov/LEplot/LEplot2001/LE2011Jun15T.pdf
http://www.mreclipse.com/Special/LEnext.html
~ A l i c e !
Summer Solstice Sunset Watch – 2011
I’m back! Time for the seasonal sunset watch!
- When: Tuesday, June 21, 2011 at 9:11pm (so come at 8:45pm)
- Where: Solstice Park – all the way up the hill from the tennis courts (or, if you’re not in Seattle, wherever you have a view of the western horizon!)
- Who: Everyone welcome, as usual.
Sunset on June 21, 2011 at 9pm Credit: Jason Gift Enevoldsen
Come watch the summer solstice sunset at Solstice Park in West Seattle on Tuesday the 21st. We’ll see if the sunset lines up with the placed marker. I’ll be there even if it is cloudy because sometimes the Sun peeks through just as it begins to set, but if it is driving rain I’m staying home.
If you’re interested – here’s the timing of various celestial events on Saturday from Seattle, courtesy of the U.S. Naval Observatory Astronomical Applications Department:
Sun and Moon Data for One Day
The following information is provided for Seattle, King County, Washington (longitude W122.3, latitude N47.6):
Tuesday 21 June 2011 Pacific Daylight Time
SUN
Begin civil twilight 4:31 a.m.
Sunrise 5:11 a.m.
Sun transit 1:11 p.m.
Sunset 9:11 p.m.
End civil twilight 9:52 p.m.MOON
Moonrise 11:56 p.m. on preceding day
Moon transit 5:43 a.m.
Moonset 11:41 a.m.
Moonrise 12:16 a.m. on following day
This event is my part of the NASA’s Solar System Ambassadors program, and thanks to West Seattle Blog for publicizing the last few!
Everyone is welcome, see you there!
~ A l i c e !
