New Horizons and Ultima Thule

New Horizons and Ultima Thule

Just after midnight on January 1st, the New Horizons spacecraft will have its close encounter with the Kuiper Belt object Ultima Thule, also known as (486958) 2014 MU69. Since New Horizons flew by Pluto in July 2015 it has been preparing for this moment. Ultima Thule wasn’t even targeted until after the Pluto encounter was over, and it was only discovered in 2014. 

New Horizons spacecraft

Of course, the next thing is simulating the encounter in Starry Night. The first problem here is that the mission path provided for New Horizons in Starry Night doesn’t extend to the present day. However, the JPL HORIZONS service can provide updated state vectors, which I have put into the attached file New Horizons.xyz.

To get the updated mission path of New Horizons into your SciDome, download this zip, open it, and copy “New Horizons.xyz” into this folder on your Preflight computer running SciDome Version 7:

C:\ProgramData\Simulation Curriculum\Starry Night Prefs\Sky Data\Space Missions

This is a networked folder that exists on both Preflight and Renderbox computers, so the file only needs to be in one place in order to be accessible in both computers. If there is no “Space Missions” subfolder of this SkyData folder, you may have to create it. Although there will then be more than one version of the New Horizons file on your system, this one will take precedence.

Ultima Thule imagery captured by New Horizons

Next, we have to add Ultima Thule to Starry Night. I find the best way to do this is to right-click on the Sun and in the details window that pops up, select ‘New Asteroid…’ In the ‘Asteroid: Untitled’ window that pops up, enter the following data, which comes from the Minor Planet Center at Harvard:

Name: Ultima Thule
Mean Distance: 44.581400  
Eccentricity: 0.041725   
Inclination: 2.4512  
Ascending Node: 158.9977  
Arg of Pericentre: 174.4177  
Mean Anomaly: 316.5508  
Epoch: 2458600.5

Exit this window and answer the prompt, ‘Do you want to save changes…?’ with yes. The next time you quit Starry Night, this new object will be saved into a file called “User Planets.ssd” that lives on your Preflight computer, but is not automatically networked to the Renderbox. In order to get it to live on the Renderbox, you have to find “User Planets.ssd” and copy it into part of the Sky Data folder we looked at above.

Locate ‘User Planets.ssd’ in the following folder:

C:\Users\SPITZ\AppData\Local\Simulation Curriculum\Starry Night Prefs\Preflight\

Verify that this file was last modified on the date you are doing this work. 

The destination the file should be copied to is:

C:\ProgramData\Simulation Curriculum\Starry Night Prefs\Sky Data\

If there is an older version of ‘User Planets.ssd’ in the destination, better save it to a safe location, just in case.

The Ultima Thule encounter could be a strange one. Pluto is about as big as the United States, from the 49th parallel to the Rio Grande, but Ultima Thule is only about as big as Nantucket Sound. Its shape has been worked out from occultations, and it looks elongated, not round. You can get more data about the mission to share from this blog entry from Emily Lakdawalla at the Planetary Society.

You can run a simulation of the encounter on your phone with the free Pluto Safari app from Simulation Curriculum, our partners in developing Starry Night Dome and The Layered Earth Dome for SciDome planetariums.

Simulating Apollo 8 on SciDome

Simulating Apollo 8 on SciDome

Tomorrow, Friday, will be the 50th anniversary of the launch of Apollo 8, the first crewed space flight to orbit the Moon. You can simulate Apollo 8, and the other eight Apollo missions that went to the Moon, on your SciDome.

Apollo 8 mission patch, showing the “figure 8” path the spacecraft travelled from the Earth to the Moon

First, make sure that ‘Space Missions’ are checked to be visible in your View Options pane. If you type in ‘Apollo’ in the Starry Night search engine pane, each mission will come up, and you can break each one down by “Mission Path segments” that each describe a phase of flight, and look at the Command Module and Lunar Module separately at relevant points.

These missions can only be seen when Starry Night is displaying the right time between 1968 and 1972, which you can get by right-clicking on the mission you want and selecting “Set Time to Mission Event…” and picking “Launch”, for example. The best way to see the mission path of Apollo is to be looking at it from well above the Earth’s surface, with ‘Hover as Earth Rotates’ set so that the Earth’s surface can rotate underneath you and the fixed stars stay fixed on the dome.

Apollo 8 follows a curving path out from the Earth to the Moon, orbits around the Moon ten times, and then returns to the Earth. The different mission path segments are different colors. 

You can see that the spacecraft orbits around the Moon from lunar west to lunar east. However, when we look up at Apollo’s path around the Moon it appears to be opposite the path that spacecraft orbit the Earth, even though everything launched from Cape Canaveral also goes towards the east. The Apollo spacecraft were launched into a figure-eight trajectory, so the “patching of conics” that reverses the frame of reference is like when two people shake hands on their right side. From one person’s point of view the other person is shaking their left hand, even though both participants are using their right.

The Apollo spacecraft and the Saturn V rocket are rendered in 3D in Starry Night if you go to them and look at them up close. The Apollo 8 spacecraft is pointed at the Earth by default.

Apollo 8 “Earthrise” photo

The famous “Earthrise” photo was taken at the beginning of the fourth orbit, on December 24th, 1968, at about 16:25 Universal Time, as shown in SciDome. There is some question of which of the three astronauts – Commander Frank Borman, Command Module Pilot Jim Lovell, or “Lunar Module” Pilot Bill Anders – took the photo, and the question was resolved by Apollo historian Andrew Chaikin, who recounts his investigations in Smithsonian Magazine.

In Starry Night Preflight’s ‘SkyGuide’ pane there is a section on the Apollo missions, and Apollo 8 has 13 sub-headings that go into phases of flight like the Earthrise photo in some detail. Each subheading calls up a Starry Night application favourite scene that describes that phase of flight, with some text and images that appear in the SkyGuide pane.

Sulawesi Earthquake in The Layered Earth

Sulawesi Earthquake in The Layered Earth

When we’ve been discussing applications of Starry Night in the dome, there was usually little need to worry about the human element, but with The Layered Earth (TLE) this is different. Most of the layers we use and stories we’re going to tell are about consequences that profoundly affect humanity.

2018 Sulawesi earthquake and aftershocks

Earlier today a large earthquake struck Sulawesi, an island in Indonesia. There’s a cluster of shallow (red) tremor marks on TLE’s 7-day USGS Earthquake Data layer, but if your SciTouch can’t identify the main M 7.5 event, please check the layer’s “settings”. 7.5 is actually the maximum strength of quakes that can be shown with this layer, and the layer settings may specify and earthquake like this is “offscale high” unless you widen the scale.

In TLE, shallow earthquakes are displayed as red, intermediate ones as yellow, and deep quakes are green (and earthquakes above sea level are white.) These colors conceptually indicate that shallow earthquakes are more dangerous.

A tsunami caused by this earthquake appears to have devastated the city of Palu, which is very close to the epicenter of the quake. Palu is located at the far end of a long bay that opens out onto the Makassar Strait. The effect of the tsunami may have been magnified by the shape of the bay. Social media is already carrying video of the tsunami that’s comparable to the 2004 Indian Ocean and 2011 Tohoku events.

The Makassar Strait is not a tectonic plate boundary that can be seen in TLE, but Indonesia is located at the convergence of several plates and there are lots of tectonic fault lines that are not located on plate boundaries. The Palu-Koro Trandform Fault can be seen in TLE in the indent under “Fault Types” layers, and the “Global Strain Rate” layer is red in that area.

The earthquake was detected at Greenville, DE even though the range to the earthquake (15323 km, or 138°) puts it inside the “shadow zone” created by refraction of primary vibrations off of the outer edge of the Earth’s liquid outer core. Weaker earthquakes that are between 104° and 140° away from the detector generally aren’t picked up because of the “shadow zone”, but stronger ones generate enough primary and secondary vibrations that the shaking is picked up worldwide. But it takes longer for these waves to be picked up. If you’ve experienced an earthquake you may have felt the gap between the arrival of primary and then secondary vibrations.

Mission Impossible: Ghost Particle

Mission Impossible: Ghost Particle

Earlier this month, another “multi-messenger” announcement was made of the discovery of a new astronomical outburst by different instruments that study different parts of the universe. The first major multi-messenger astronomy discovery was announced last year after the collision of two neutron stars was observed in the nearby galaxy NGC 4993. The neutron star collision was observed first with the LIGO and Virgo gravitational wave detectors, coincident with a gamma ray burst detected by the Fermi space telescope, pinpointed with an optical telescope in South America, and followed up with different kinds of detectors.

IceCube Neutrino Observatory diagram
from IceCube Science Team

This new announcement is based on the detection of a very unusual neutrino or “ghost particle” at the IceCube Neutrino Observatory at the South Pole. This event is worth pointing out in SciDome because we have a horizon panorama that matches the horizon at the South Pole, and one or two other points that may help students understand how the sky works and what neutrinos are.

Neutrinos have been observed with detectors in both the northern and southern hemispheres of Earth, and they are created as a byproduct of various nuclear reactions. Neutrinos hardly interact with normal matter at all, and they tend to radiate outwards from their point of creation at the speed of light.

Neutrinos at rest were assumed to be massless until evidence to the otherwise shown by Art McDonald and Raymond Davis, Jr., led to them being awarded the Nobel Prize in Physics in 2015.

The interaction of neutrinos with normal matter is so weak that most neutrinos that encounter the Earth fly straight through it without hitting anything. In February 1987 when a nearby supernova popped off in the Large Magellanic Cloud, 25 neutrinos were detected at neutrino observatories in the northern hemisphere, where the Large Magellanic Cloud never rises above the horizon.

The new neutrino detection from IceCube at the South Pole was detailed enough to provide a vector back to its point of origin, somewhere within a 1.3-degree-wide circle on the sky.

The Spitz Fulldome Curriculum, included with every SciDome system, includes dozens of lessons prepared by noted astronomy educator Dr. David Bradstreet

The circle enclosed a radio source discovered in 1983, a galaxy 3.7 billion light years away with an active supermassive black hole at its core. This is one of the quasars like Dr. Bradstreet uses in his “Quasars Fulldome” show from the Fulldome Curriculum Vol. 3. Because this quasar’s jet is pointed at us, it is called a “blazar”; this term originated because the first of its type happened to be named “BL Lacertae”, and because blazars can appear brighter than normal quasars and their brightness can vary more quickly than normal quasars.

Like before, this neutrino detected from the South Pole had flown through the Earth to get to the detector. The blazar TXS 0506+056 is located at about 5 hours right ascension and +5° north of the celestial equator. Only objects south of the celestial equator are above the horizon as seen from the South Pole.

TXS 0506+056 is conveniently located in the Shield of Orion, part of the most easily recognized equatorial constellation on the sky. The blazar is labeled “MG 0509 +0541” in SciDome and is one of the quasars in Dr. Bradstreet’s “Galactocentric Distributions” minilesson.

In the part of the Fulldome Curriculum “Seasons” class that visits the South Pole, the audience may have a hard time recognizing Orion because it is upside down and its northern half, including TXS 0506+056 is below the horizon. The horizon needs to be switched off and then tilted up to bring the rest of the constellation into view to simulate a “neutrino filter”.

The prefix TXS stands for ‘Texas’, where UT-Austin astronomers set up a radio telescope array outside of Marfa for several years in the 1980s – now removed. MG stands for ‘MIT-Green Bank Observatory’.

The mass of neutrinos and other particles is calculated in electron volts, but because they are so small, only particles that have a large amount of kinetic energy are comparable to things that we can comprehend. 1 trillion electron volts (1 TeV using the prefix tera-) is comparable to the kinetic energy of a mosquito in flight. The most powerful cosmic ray ever detected had a mass of 300 quintillion electron volts, comparable to a pitched baseball.

The single neutrino detected by IceCube from TXS 0506+056 had a mass of 290 TeV. After crossing 3.7 billion light years in space, this is by far the most distant neutrino emission ever detected: the only other objects in the sky that have produced detected neutrinos have been the Sun (8 light-minutes away) and Supernova 1987A (168,000 light-years.)

(In 2012, the IceCube Collaboration detected three other high-energy neutrinos, which they named Bert, Ernie and Big Bird, but where Bert and Ernie came from is not known, and Big Bird was probably generated by the blazar PKS B1424-418 with a certainty of 95%. That’s only two sigma, which does not hold water with particle physicists who have much stricter statistical significance limits. TXS 0506+56 was much more narrowly confined.)

Because matter and energy are relative, an electron volt is equivalent to the energy exchanged by the charge of a single electron moving across an electric potential difference of one volt. The only way a neutrino can be detected is on the rare occasion when it enters a neutrino detector (like a large underground tank of heavy water or tetrachloroethylene or linear alkylbenzene or another chemical) and collides with an atomic nucleus or an electron inside the detector, emitting light that can be detected with photomultiplier tubes. IceCube is unusual because its detectors have been drilled into the Antarctic ice pack and are not suspended in water or another fluid.

Visitor from interstellar space

Visitor from interstellar space

By now I hope you’re heard about the interstellar interloper that’s been passing through the inner solar system recently. This asteroid, which has been named ‘Oumuamua, is the first-ever discovered object that has been observed coming into the solar system from elsewhere in the Milky Way that is larger than tiny bits of dust.

There are several known instances of objects being “ejected” out of our solar system, so periodically there should be a chance to see a passing object that has been “ejected” from some other solar system passing by us. But only objects that pass close to the Sun or those that cast their own light are bright enough to be seen.

‘Oumuamua (NASA artist’s impression)

‘Oumuamua was discovered on Oct. 19th when it was already more than a month past its closest point to the Sun. It’s only about 300 feet across, and it was close enough to Earth to be seen for a short while.

Objects passing through the solar system that aren’t gravitationally bound to the Sun must be moving very quickly, although all paths are bent around their closest point to the Sun. The eccentricity of an elliptical orbit around the Sun is represented in the mathematical elements of the orbit by a number between zero and 1. The eccentricity of an object that is going too fast to be captured by the Sun has a value between 1 and infinity. The value in this case is about 1.2, and the object’s velocity entering the solar system was about 59,000 mph. It was probably ejected from another star many light years away and millions of years ago, although it is from the “disk” of the Milky Way and not the more exotic “halo”. A “halo” object would probably be moving faster.

‘Oumuamua’s orbit can be simulated in Starry Night Dome. The orbital elements are a little on the uncertain side because of the short duration of observations between discovery and it zipping out of range. And the effect of the over-unity eccentricity appears to “break” the position of the object during times before February 2016 or after March 2019. But the 3 years when it’s at its closest point to the Sun are replicated pretty well.

To add ‘Oumuamua to SciDome Version 7, right-click on the Sun in Starry Night Preflight and select ‘New Asteroid…’ and enter the following values in the details window that pops up, using the ‘Pericentric’ method instead of ‘Near-Circular.’ Also pick an appropriate name in the ‘Untitled’ field.

E=1.1993471
Q=0.2552817
Node=24.5994750
W=241.6917568
I=122.6813370
Tp=2458005.98918377
Epoch=2458056.5

Once you close this details window and “keep” the new object, and quit SciDome properly, the new object will be written to a file called “User Planets.ssd”. You need to copy this file from its location on Preflight to the Renderbox for it to be “live” on both computers.

c:\Users\Spitz\AppData\Local\Simulation Curriculum\Starry Night Prefs\Preflight\User Planets.ssd

This file needs to be copied and installed on the Renderbox at the comparable folder location:

c:\Users\Spitz\AppData\Local\Simulation Curriculum\Starry Night Prefs\Renderbox\User Planets.ssd

Please contact me if you need a little extra guidance on making this work. After this is done, the object should be “live” in Starry Night on the dome during the current “Now”.

You can also fly out to the object and watch the planets and the Sun fly by as its lumpy asteroid shape zooms past. I would recommend one special piece of orientation for objects like this. During SciDome training, one of the choices we emphasize when looking at a solar system object from above is that you can “Rotate With” or “Hover Over” the planet or moon below. If you “Rotate With” while looking down at the United States, and speed up time, the Earth won’t appear to rotate, you can see successive nightfalls and daybreaks over North America, and the background stars will rotate around in the background. If you “Hover Over”, as time passes North America will rotate away to the east, Asia will appear out of the west and the fixed stars won’t move. The Sun Angle won’t change much either.

There is a third option in the dropdown menu that allows you to choose “Rotate With” or “Hover Over”, which is very much like “Hover Over” but not quite. It’s called “Follow in Orbit.” The small difference between “Hover Over” and “Follow in Orbit” is that “Follow in Orbit” will maintain the phase of illumination by the Sun as the planet orbits the Sun, and the fixed stars will slowly sweep by although the Sun Angle won’t change as time passes. “Hover Over” is completely inertial – as the planet orbits the Sun, the phase of the Sun Angle will slowly change and only the fixed stars will stay fixed.

We don’t always drill down far enough to distinguish between “Hover Over” and “Follow in Orbit” because it takes more than a month of time flow to accumulate a 30° difference between the two. But in the case of ‘Oumuamua, because its position with respect to the Sun changes so quickly, you might want a way to keep the Sun Angle constant so the source of illumination won’t rotate away from your point of view and you “lose the light”. “Follow in Orbit” is a useful orientation choice for an object like this.

A little bit of hay has been made of the way the incoming path of ‘Oumuamua leads back towards the constellation Lyra. This can also be simulated in Starry Night. The brightest star in Lyra is Vega, which was the fictional location of the first extraterrestrial signals in the Carl Sagan novel Contact. Sagan may have picked Vega to use in his book because it has been known for some time that the motion of the Sun and the solar system through the Milky Way is in the general direction of that star.

The great American/Canadian astronomer Simon Newcomb wrote in Elements of Astronomy – a book Sagan would have known – “The motion of our solar system toward the constellation Lyra is one of the most wonderful conclusions of modern astronomy.” However, as we move in the direction of that constellation, Lyra and the other stars in it have their own movements that will scramble them all out in other directions as time passes.

The proper motions of the stars can also be turned on in Starry Night as a series of artificial lines, and simulated back and forth through a couple of hundred thousand years of movement centered on the present if you switch to a “Stationary Location.” These proper motions may appear random, but if you highlight some of the closest and most well-known nearby stars, you can track them moving away from or toward the direction of Lyra as time passes forward or backward with some coherence.