Welcome to the latest installment of my space science e-mail. A lot has been happening in astronomy lately — enough to keep textbook writers like myself scrambling to keep up with it! I don’t have enough time right now to cover all of it in one e-mail, so some news items will have to wait until a future e-mail. Here’s what I have for this time:
1. Who ordered the extra pizza? The discovery of an"Planet X."
2. Mars Reconnaissance Orbiter launch tomorrow!
3. Perseid meteor shower peaks early morning August 12.
4. Mars will NOT be super bright on Aug. 27.
5. What next for the Shuttle? My editorial opinion…
6. Max Goes to Schools: Update on my 5,000 book donation program.
Read on below…
1. Who ordered the extra pizza?
You’ve probably heard the mnemonic for remembering the order of the planets that goes "My very excellent mother just sent us nine pizzas." Well, as you may have read, someone ordered another pizza! On July 29, astronomers announced the discovery of an icy object in our outer solar system that is as big as or slightly bigger than Pluto; NASA Science News has a report on the discovery. For the moment, the object is being referred to as "Planet X," though it is likely to get an official name soon. What does this discovery mean? Here are a few key points:
- The discovery was NOT a big surprise. We’ve known for more than a decade that Pluto is one of many relatively large, icy objects — essentially large comets — that orbit the Sun beyond Neptune, in a region of our solar system called the Kuiper (pronounced koy-per) Belt. Until this new discovery, Pluto was the largest known object in the Kuiper Belt, but many objects that are fairly close in size to Pluto have been discovered in recent years. It seemed only a matter of time before we found another object as large as Pluto, and now it has happened. Even today, less than about half the Kuiper Belt has been carefully searched with telescopes, so it is possible that other Pluto-size objects remain to be discovered.
- The discovery will force astronomers to confront the question of whether Pluto should count as a planet. We’ve known for several decades that Pluto is quite different in character from the other 8 planets. Besides being the most distant planet with the most unusual orbit around the Sun, it is much smaller than any of the other planets — its mass is only about 0.2% that of Earth. Moreover, Pluto’s composition of ice and rock makes it much more similar to the thousands of known comets than to the other eight planets. Some people have therefore argued that Pluto should be demoted from "planet" to "large comet" (or "large Kuiper belt object"). Others have argued that other large objects found in the Kuiper belt (or elsewhere in our solar system) should be promoted to being planets as well. The status quo has been to say that Pluto retains its planetary designation due to the fact that we’ve been calling it a planet since its discovery in 1930, while the other large Kuiper belt objects are just considered large comets. The new discovery disrupts this status quo, because it would be very strange to say that Pluto is a planet but an even larger object is not. Thus….
- The number of planets in our solar system is no longer clear — but it is NOT NINE! With the new discovery, we face at least 3 options in counting planets: (1) If we decide that objects like Pluto are too small to be planets, then the new object is also too small because it is so close in size to Pluto. Then there are 8 planets in our solar system. (2) If we decide that Pluto represents the minimum size cutoff, then the new object also makes it, and there are 10 planets in our solar system — and it’s possible that other Pluto-size objects still remain to be discovered; (3) Or we could decide that the minimum size cutoff is somewhat smaller than Pluto, in which case the number of known planets in our solar system could be 12, 15, 20, or many other numbers, depending on exactly where we place the cutoff.
Questions/activities for class:
- Compare the planets to scale: Build scale models of Earth, Jupiter, and Pluto so that you can see how they compare in size. Data you’ll need: Jupiter’s diameter is 11.2 times that of Earth; Pluto’s diameter is 0.18 times that of Earth.
- How many planets are in our solar system? Discuss the various options for counting planets, and form an opinion about how we should answer this question.
- Name Planet X: The official name of the new object will be decided by the International Astronomical Union. But in the meantime, suggest your own name for the new planet.
- Web search: Kuiper belt objects. Use the web to find out about other large Kuiper belt objects discovered in recent years. Make a list of the 5 largest after Pluto, and their estimated sizes.
- Research: Size estimates. As you learn about Kuiper belt objects, you’ll see that their sizes are usually given as rough estimates rather than more exact values. Find out why.
2. Mars Reconnaissance Orbiter (MRO) scheduled for launch.
NASA’s next mission to Mars, an orbiter that should give us much better global views of the surface than ever before, is tentatively scheduled for launch TOMORROW (Aug. 10). Read more at the mission’s home page.
Questions for class:
- By studying the MRO web site, make a list of the key capabilities of MRO that exceed those of prior Mars orbiters.
- What are the major things that scientists hope to learn about Mars from MRO?
- What other spacecraft are currently studying Mars? (Answer: 3 other orbiters — Mars Global Surveyor, Mars Odyssey, and Mars Express — plus the two rovers, Spirit and Opportunity, on the ground.)
3. Perseid meteor shower peaks early morning August 12.
The annual Perseid meteor shower is well worth watching. As usual for meteor showers, the best time to watch is before dawn — say, between 2 am and 5 am. Any dark site will do — you just need a clear view of the sky. No equipment needed; in fact, it’s best to use your naked eye and as much peripheral vision as possible, so you can catch meteors in all directions. More info on this year’s shower here. Be sure to note that the MORNING of Aug. 12 means you need to set your alarm on the NIGHT of Aug. 11.
4. Mars will NOT be super bright on Aug. 27.
Perhaps you’ve seen the e-mails circulating that claim that Mars will be super bright on Aug. 27. Sounds cool, but it’s just NOT TRUE. Read more about this "Mars hoax" here.
Questions for class:
- When will Mars really be at its brightest this year? (Answer: Oct. 30).
- Why will Mars be at its brightest at that time? (Answer: That is when it is closest to Earth as both planets orbit the Sun. Propaganda: My new children’s book, Max Goes to Mars, has an end-of-book activity that will help you understand the appearance of Mars in our night sky.)
- At its brightest, how will Mars compare in brightness to the full moon? (Answer: you can calculate if you wish, but the key point is that it is WAY dimmer than the full moon, and also much smaller in angular size.)
5. What next for the Shuttle?
Hey, it’s my e-mail, so I’ll editorialize if I want to… We’re all very relieved at the successful landing of the Space Shuttle Discovery this morning. It is truly an amazing spacecraft, and NASA should be commended for its safe launch and return — but the Shuttle program is also more than 20 years old and built with even older technology. With Shuttles now grounded again while NASA seeks to solve more safety problems, it’s a good time to ask what should be next for the Shuttle. I have a fairly strong personal opinion on this question, based on the following key points:
- I’m a huge supporter of NASA’s Moon/Mars initiative (see the article I wrote), but the current NASA budget is not large enough to do the initiative justice.
- The Shuttle and Station consume the bulk of NASA’s current budget.
- One way or other, the Shuttle is going to be "retired" within the next few years anyway.
- The Station has been scaled down so much from early visions that it is capable of doing very little useful science of any kind.
- Aside from completing the Station, the only remaining important mission for the Shuttle would be the repair of the Hubble Space Telescope — but I’d wager that the cost of fixing/upgrading the Shuttle for such a flight will turn out to be greater than the cost of building and launching an entirely new space telescope.
The obvious conclusion, at least in my opinion: Cancel the Shuttle and Station programs now, and redirect the money into the Moon/Mars initiative. Divert a small portion of the money to quickly building and launching a replacement for Hubble. The only potential downsides that I’ve heard to this plan are that it could affect Shuttle-related jobs and might anger our international partners working on the Space Station, but both complaints seem unfounded: As long as the money goes to new space initiatives, jobs will be changed but not lost, and it’s hard for me to believe that our partners wouldn’t actually PREFER to redirect their efforts toward the Moon and Mars rather than low-Earth orbit.
6. Max Goes to Schools update.
As you are probably aware from prior e-mails, I am donating 5,000 copies of Max Goes to Mars to public school libraries around the nation; click here for info about the program. As of today, all but about 600 of the 5,000 copies have been claimed by various school districts, so if you are still looking into this for your district, please hurry. If you’re waiting for the new book: It has been printed and will be in our distributor’s warehouse by the end of the month. The books for schools should arrive in September, and it should arrive in bookstores by October 1.
All for now!
Jeff