Image text: The SLS head engineer plans to invite Shania Twain to stand under the completed prototype, then tell her, 'I don't expect you to date me just because I'm a rocket scientist, but you've gotta admit--this is pretty fucking impressive.'

SLS, which stands for Space Launch System (naturally) is the new launch program being designed by NASA to replace the retired Space Shuttle launch system.  In the first frame, Cueball is showing Black Hat something about the SLS, possibly a video on his phone or other portable electronic device.

As usually with his appearances, Black Hat is causing trouble.  Here, Black Hat is by as much as I can find, telling the truth, because Nazi-Germany era scientists like Wernher von Braun, who was one of the developers of the Saturn V launch vehicle, came over to NASA and helped develop NASA's space program.

Black Hat's assumption in the last frame is obviously a bridge too far (which is where the joke is in the comic), but he gets his desired reaction out of Cueball, who is hanging his head.

Shania Twain comes into this comic in the image text because in her song "That Don't Impress Me Much", she sings: "Okay, so you're a rocket scientist/That don't impress me much".  But, the image text argues that if she stood under the new SLS prototype, she would admit it was in fact, impressive.

Image text: Type II Kardashev civilizations eventually completely enclose their planetary system in a Dyson sphere because space is way too big to look at all the time.

In this comic, Professor Cueball is suggesting an "Occulting Telescope", which follows directly with the definition of an occultation (thanks Wikipedia!) which is an event that occurs when one object is hidden by another object that passes between it and the observer.  This telescope sees a star, then positions a disc between itself and the star, occulting itself and Earth from the light from the star.

The reasoning for this maneuver is that Professor Cueball thinks there are too many stars (as he says in the last frame).

In the image text, The Kardashev scale (thanks Wikipedia!) is a method of measuring an advanced civilization's level of technological advancement. The scale has three designated categories called Type I, II, and III. These are based on the amount of usable energy a civilization has at its disposal, and the degree of space colonization. In general terms, a Type I civilization has achieved mastery of the resources of its home planet, Type II of its solar system, and Type III of its galaxy.  One of the properties of a Kardashev type II civilization is the creation of a Dyson sphere around a planet to contain all its energy.  And lastly, a Dyson Sphere (Wiki'ed!) is a hypothetical megastructure originally described by Freeman Dyson. Such a "sphere" would be a system of orbiting solar power satellites meant to completely encompass a star and capture most or all of its energy output.

This comic's image text says that the secondary benefit from a Dyson sphere is that it obscures (or completes the occultation of) all those pesky stars.

Image text: If you fire a Portal gun through the door of the wardrobe, space and time knot together, which leads to a frustrated Aslan trying to impart Christian morality to the Space sphere.

This comic was posted late and now I'm late and I'm at work so I can't do as much explaining as I usually do, but I'll do my best.  That's also why we have the best comment section on the Internet.

The basic idea of the formula and the comic are based on the books and movies of the Lion, the Witch and the Wardrobe in which a giant wardrobe contains a portal to a world known as Narnia. In the comic, someone connects an anchor to the wardrobe and throws it into the ocean which means that a steady stream of water at a velocity of 200 m/s will flow into Narnia.

The White Witch, the antagonist in the books and movies apparently won't know what hit her according to the caption.

The image text references the video game "Portal" in which you fire a portal gun into walls and etc to make "portals" that can open holes in other places so that you may portal through.

The image text also references the fact that CS Lewis wrote the Lion, Witch and Wardrobe books as a thinly veiled allegory of Christ's crucifixion with Aslan, the Lion in the title, playing Christ's part.  (Spoiler alert! Sorry!)

This is a classic xkcd based on the intersection of literature, math and video games.

Image text: And no avian society ever develops space travel because it's impossible to focus on calculus when you could be outside flying.

Jeb Corliss is a professional BASE jumper and wingsuit flyer (similar to the wingsuit you can see in the 4th frame).  Corliss has jumped from a lot of different buildings and monuments in the world.  Hence, the Corliss Resolution.

In this comic, which is well explained by its own captions - life in general decides to find an activity that is more fun than survival, like flying off a cliff in a wingsuit, rather than working on space colonization.  And as the image text adds on to that, flying is more fun that working on calculus.

Image text: The universe is probably littered with the one-planet graves of cultures which made the sensible economic decision that there's no good reason to go into space--each discovered, studied, and remembered by the ones who made the irrational decision.

In this comic, over 65 years, Randall is projecting the number of living humans who have walked on another word (which I believe counts the moon).  He is using actuarial tables or life tables which shows for each age the probability that a certain person will be alive by their next birthday.

This comic, obviously assumes that no one else is going to walk on another world going forward into the future.  Which, as is mentioned in the image text, is a terrible idea for the future of the human race.  If the human race only exists on one planet - one disaster can destroy the whole race.  However, if humans extend their society to other planets, they lessen the risk of complete extinction.

Personally, I hope the graph above does not come true and the number of living humans who have walked on another world actually increases instead of decreases.

Image text: I think the IETF hit the right balance with the 128 bits thing. We can fit MAC addresses in a /64 subnet, and the nanobots will only be able to devour half the planet.

So, in this comic, the two characters are in orbit in space while evil nanobots are devouring the earth in a swarm.  The nanobots stop after devouring 40% of the planet.  This is a take on the "gray goo" scenario in which self-replicating nanobots destroy the earth while creating more and more of themselves non-stop.

However, the nanobots are only able to destroy 40% of the planet because (psedo math ahead!) 40% of the earth mass = (# of IPv6 addresses) x (A few cubic microns).  Without more IP addresses, the nanobots cannot continue to replicate.

This is a joke on the current state of events in which the internet is currently running out of IPv4 addresses.  The only difference is that we are on IPv4 and the nanobots are on IPv6.

1998 is when the first IP address registry was opened and IETF is the Internet Engineering Task Force.

Image text: Eärendil will patrol the walls of night only until the sun reaches red giant stage, engulfing the Morning Star on his brow. Light and high beauty are passing things as well.

The Stingray Nebula is the youngest known planetary nebula in the galaxy.  In 1987 it was an asymptotic giant branch (AGB) B1 supergiant and then became the Stingray Nebula in 1987.  Well, didn't become that in 1987, the light of the incident reached the Earth in 1987.

This comic went from a reassuring comic about stars at night giving hope in the darkness, but then as with most xkcd's, it took a turn.  In this case, the twist is that because Cueball's star he got attached to exploded into a nebula, we should only become attached to stars that aren't quite as volatile as the one that formed the Stingray Nebula.

UPDATE: Sorry for the late post, but I wrote this all out early this morning but didn't post it.  I blame it on the fact that I brushed my teeth with a bottle of Jack... (not really).

Image text: Guest comic by David Troupes of Buttercup Festival, who is living in that lovely tree outside your window.

Wow,  a Tuesday comic?  I'm thrown off, that's why this is so late.  Was not expecting that.  But, I guess with "Guest Week" anything can happen.

This one from David Troupes of Buttercup Festival, which can be found here.

Pretty straight forward, Cueball and Cutie sitting on the moon and she says that she has never been so happy.  But, then she stops herself.  Once she pegs her old high school nemesis with a rock (moon rock?!), then she can truthfully say "I've never been so happy."

Image text: Don't worry! From the light's point of view, home and your eye are in the same place, and the journey takes no time at all! Relativity saves the day again.

There appears to be two things going on in this comic, one in the comic and another in the image text.   However, the slight reference to home in the comic leads to the image text.

In the comic, Cutie and Beret are star-gazing and commenting on how far the light has traveled before they could see it here on Earth.  They comment on how beautiful the stars are when their light reaches Earth.  So, Beret grabs a picture or painting frame and holds it up, making a comment on how the stars look like art. Thanks to everyone in the comments who pointed out that it is a mirror, not a picture frame.  Beret is holding up the mirror, so the light bounces back instead of dying.

The image text is making reference to the fact that from any other stars perspective,  yourself and any other place on Earth is on the same spot.  So, the travel between the points is negligible.  I'm not sure the point of the image text, but it seems to imply homesickness.

Image text: Normally, the Shuttle can't quite safely reach the orbital inclination required to pass over both those points from a Canaveral launch, but this is an alternate history in which either it launches from Vandenburg or everyone hates the Outer Banks.

This comic is about disputed territories, orbiting satellites and latitude and longitude.

There is not enough pixels in the world to go over the Palestinan/Israeli conflict over land in the Middle East.  Needless to say as in this comic, both groups lay claim to the same area of land and have been fighting over it for years with no end in sight.

The Texas - Oklahoma disputes pale in comparison, but that is where the joke lies in the comic.  Texas and Oklahoma have been disputing their border for years as well before it was finally settled around 10 years ago.

Cueball probably should have just settled for latitude and longitude instead of trying to define where the shuttle was over.  How about just "Earth"?

Vandenburg is a reference to the Vandenburg Air Force Base which has space launch capabilities and is in Santa Barbara, California.

I'm not sure why everyone would hate the Outer Banks?  The only connection I know of is that you can see the shuttle launch from Cape Canaveral in Florida in the Outer Banks as the shuttle moves swiftly up the East Coast and into orbit.