Astronomy.com blog : Liz Kruesi

Division of Planetary Sciences meeting, Thursday recap

Liz Kruesi — Thu, 08 Oct 2009 21:45:00 GMT

Thursday was a short day at the conference. I had to check out of the hotel in the late morning, so I had time only to jump between two sessions (another exoplanet one, and one about near-Earth asteroids [NEAs]).

Editor's note: Liz is posting updates regularly from DPS09 to Twitter.com/AstronomyMag.

The exoplanet session focused on what I’ve noticed to be an extremely popular topic here at the conference — modeling exoplanet atmospheres. That’s good to hear, because a near future issue of Astronomy will feature an article about this. So make sure to keep an eye out for it!

I then headed over to the NEA session. This was interesting stuff. I haven’t heard much about Apophis lately … until these presentations. Apophis is the asteroid that was in the news about 5 years ago because astronomers predicted there was a chance as high as 1 in 37 of it slamming into Earth in 2029. Scientists quickly revised that prediction … but not after the public – and the media – freaked out about it. Now we know there’s a 0 percent chance the asteroid will hit our home planet in 2029.

There is a chance, however, that it could pass through a gravitational “keyhole.” This is a small window (about 600 meters in diameter) where the gravitational forces would set up a collision with Earth. But the chance of such a collision has now been downgraded to just 1 in 250,000 in 2036, said David Tholen of the University of Hawaii and Steven Chesley of Jet Propulsion Laboratory today at DPS. Following additional observations and modeling, Tholen’s group estimates Apophis could pass through another keyhole in 2067, which would send it on a 2068 collision course with Earth. This keyhole, however, is just 2m in diameter … that’s pretty tiny. The chance of impact is even smaller than 2036’s chances — about 1 in 333,000.

It sounds like we’re pretty safe from Apophis, but we’ll need more observations to determine whether this fact holds true for all the other NEAs out there. Upcoming large-scale surveys should provide some of these much-needed observations.

All right, I’m off to explore Puerto Rico’s El Yunque rainforest and bioluminescence bay. Then the Arecibo Observatory on Saturday.

Previous post: Wednesday recap

Division of Planetary Sciences meeting, Wednesday recap

Liz Kruesi — Thu, 08 Oct 2009 20:20:00 GMT

I started off Wednesday at a lunar science session where presenters focused on results from the Japanese Kaguya mission and the Lunar Reconnaissance Orbiter (LRO). Robert Reedy of the Planetary Science Institute discussed Kaguya maps of the Moon. The probe measured gamma rays to study the distribution of elements, and it produced the first global uranium map of the Moon.

Editor's note: Liz is posting updates regularly from DPS09 to Twitter.com/AstronomyMag.

A few presenters talked about early LRO results — that mission is already chugging out some great science. And it’s only been taking data for (depending on the instrument) 1-3 months. Benjamin Greenhagen of the Jet Propulsion Laboratory presented information about the Diviner instrument, which measures surface temperatures. Early findings with this instrument were actually in the news a few weeks ago: Scientists used this device to discover portions of the permanently shadowed regions at the Moon’s south polar region are around 35 kelvin. That means these regions are looking like the coldest areas in the solar system. Greenhagen added that we’re approaching lunar summer now, so it appears these regions are warming a small amount, but they’re still under 50 K. That’s cold.

Next I headed over to a near-Earth asteroid (NEA) session. Mike Nolan of Arecibo Observatory talked about the diversity among NEAs, which I found extremely informative. Astronomers split NEAs into the following categories: irregular bodies (potato-like), spheroids, binaries, and bars (elongated asteroids, termed “bifurcated asteroids”). The bifurcated ones look like someone smashed two play-doh spheres together. As Nolan is also the observatory director, he touched on how important radar observations of NEAs are; this is one type of research astronomers use Arecibo for. He ended his talk on a fairly sad note regarding funding for the next few years. It sounds like they have significantly less funding starting in 2011.

After a quick lunch, I sat in on another exoplanet session. This one focused on transiting exoplanets — those that pass in front of their stars from our point of view — and observing and modeling some of those planets’ atmospheres. While I already knew about this method (characterizing some extrasolar planet atmospheres), it was interesting to hear more about how the researchers do this. It sounds like this area will continue to grow … just like the entire field of exoplanet research.

To end the day, I walked through the exhibit hall and looked over some of the posters. Tomorrow I’ll bounce around between another exoplanet session and an asteroid session. Then I’m off for a day to explore the natural side of Puerto Rico (I’ll do a bit of kayaking and hiking).

On Saturday I head to Arecibo Observatory to tour the huge instrument before flying back to cold Wisconsin.

Previous post: Tuesday recap

Division of Planetary Sciences meeting, Tuesday recap

Liz Kruesi — Wed, 07 Oct 2009 19:10:00 GMT

One thing I’ve noticed at thisi year’s Division of Planetary Sciences meeting is how well members of the planetary science community support each other. Often when asking a question regarding a talk, the questioner starts out with “great talk.” It’s refreshing to see. There’s a lot of competition in the sciences (so much of a career rides on how many papers one publishes), but clearly there’s a lot of collaboration as well.

Editor's note: Liz is posting updates regularly from DPS09 to Twitter.com/AstronomyMag.

OK, back to the updates from the DPS meeting. Tuesday morning began with a few awards. First up was the first-ever Jonathan Eberhart Planetary Sciences Journalism Award, presented to Sky & Telescope Senior Contributing Editor J. Kelly Beatty. After he received his award, Clark Chapman of the Southwest Research Institute discussed Mercury and the three MESSENGER flybys. The September 29 flyby showed additional examples of volcanism, according to Chapman. The probe is scheduled to enter its science orbit around Mercury March 18, 2011, and promises more discoveries.

The next award — the Urey Prize — went to Sarah Stewart of Harvard University, for her research of impacts onto icy bodies. Then the DPS awarded the Kuiper Prize to Tobias Owen of the University of Hawaii at Monoa “for his outstanding contributions to the field of planetary science.”

Owen, “one of the fathers of the Cassini mission,” still works on the project. He gave a great lecture — it had spots of humor and covered a fairly broad topic (so that even I, with my little planetary science expertise, understood the majority of it). It sounds like he has impacted many areas in planetary science. It was a pleasure sitting in on his talk.

At lunch I tried driving to a grocery store only to discover that none of the streets in Fajardo, Puerto Rico, is labeled. Mission failed.

The second half of the day switched gears and was filled with science sessions, so I tried to jump around to a few different ones.

First I attended a session about irregular satellite debris belts. Anne Verbiscer of the University of Virginia announced her team’s discovery of an enormous dust ring around Saturn. Douglas Hamilton of the University of Maryland followed with additional details. This ring is the largest known planetary ring in the solar system. It’s some 40 times Saturn’s radius (Rsat) high. Its inner edge starts around 128 Rsat out from Saturn and extends to 207 Rsat. The ring seems to be inclined 27 degrees to Saturn’s equatorial plane.

The team observed this huge ring with the Spitzer Space Telescope. Saturn’s irregular satellite, Phoebe, is within the ring. The team described how impacts with Phoebe produced debris that remains in a thick disk around the satellite’s orbit, therefore creating this huge ring. Hamilton explained that if you were standing within the ring, the density is such that you’d be hit by a particle about once per minute — that’s a pretty low density. The October 7 issue of Nature includes the team’s study.

After sitting in on a few presentations in a session about Titan’s surface, I stopped by a science discussion about the atmospheres of jovian planets. In this presentation, Teresa Del Rio Gaztelurrutia of the Universidad del Pais in Vasco, Spain, described a long-lived cyclone in Saturn’s atmosphere. This cyclone has been around for at least 4 years (Cassini instruments have observed it from June 2004 through May 2008).

Wednesday looks like another jam-packed day. I’m definitely looking forward to wandering through the exhibit hall to view the posters.

Previous post: Monday recap

Division of Planetary Sciences meeting, Monday recap

Liz Kruesi — Tue, 06 Oct 2009 18:43:00 GMT

Monday was my first day at the 2009 Division of Planetary Sciences meeting in Puerto Rico. Unfortunately, I was off to a late start because of one of the worst migraines of my life. But I did get to the afternoon science sessions.

Editor's note: Liz is posting updates regularly from DPS09 to Twitter.com/AstronomyMag.

I spent the early afternoon at the Titan science session. Nine scientists talked about the saturnian satellite’s atmosphere and geological features. William Smythe of the Jet Propulsion Laboratory discussed his team’s deduction that transient features seen on Titan are likely patches of pure ammonia frost. These features are too close to the ground to be clouds, so they’re either ground fog or surface coating. When scientists look at the features’ spectral signatures, they most closely match ammonia.

Ralph Lorenz of the Johns Hopkins University Applied Physics Laboratory discussed his team’s (and other groups’) observations of Titan’s brightness and how it changes over time. Lorenz summed up almost 40 years of observations (starting in the early 1970s). Various astronomers started observing Titan in 1972 and saw that it was brightening … but then it started darkening.

Since then, astronomers have determined that the northern hemisphere is some 20 percent darker than the southern. Seasonal changes could explain the observed brightness changes, but this doesn’t explain the full amplitude of brightness changes. Plus, the cycle isn’t perfectly symmetric, and right now Titan is darker than previously recorded. Why could this be? The Lorenz group thinks there is something going on with Titan’s haze layers, which could be affecting the observed brightness.

In the late afternoon I sat in on a session about rocky extrasolar planets. After quite a few technical problems, the program started. This session was filled with what to look for when trying to detect earthlike planets and life on those planets. A few talks focused on what our Earth looks like from a distance (this is data that the EPOXI mission was able to collect), and therefore what we should look for in similar planets.

Editor’s note: EPOXI is a combination of the names for two extended mission components: a search for extrasolar planets during the cruise to Hartley 2, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact eXtended Investigation (DIXI).

Carolyn Crow of the University of Maryland talked about EPOXI observations of Earth and the Moon using seven spectral filters. Crow and colleagues compared those Earth observations with spectra of the other planets, and found that in low resolutions Earth is brighter than the others with certain filters.

Eliza Miller-Ricci of Harvard University discussed a possible way to directly image terrestrial planets. Back in November 2008, astronomers announced that they had directly imaged gas giant planets orbiting their stars in two systems. However, gas giant planets hold onto their initial heat (from formation) for longer than rocky planets, so astronomers have a better chance of finding a young gas giant planet than a rocky one. Miller-Ricci (and colleagues) recommended that, instead, astronomers might want to search for the afterglow of a young super-Earth collision. (As we know from the formation of Earth, a Mars-sized object initially slammed into the forming Earth. Such collisions are likely typical in young solar systems.)

The surfaces of these super-Earths will be hot initially (1,500 to 4,000 K) and cool in free space within about 100,000 years. However, if the object has a thick atmosphere, it takes 1 to 10 million years to cool. So maybe 10 percent of young stars have hot super-Earth afterglows at any given time.

There was a lot of information that came out of Monday’s sessions. Tuesday should be similar, with the addition of three major talks in the morning, given by three scientists awarded DPS prizes for their research.

On the road: The 2009 Division of Planetary Sciences meeting

Liz Kruesi — Mon, 05 Oct 2009 19:13:00 GMT

This week I’m in Fajardo, Puerto Rico, at the Division of Planetary Sciences meeting. I’ll be blogging daily and posting updates regularly to our Twitter, Facebook, and MySpace pages.

Then on Saturday I’ll have the opportunity to tour Arecibo Observatory, which is a once-in-a-lifetime experience. It should be a good week, filled with lots of news, science updates, and humid temperatures.

Tell us about International Year of Astronomy’s impact

Liz Kruesi — Thu, 10 Sep 2009 13:50:00 GMT

As I mentioned a few weeks ago, I’m working on Astronomy’s article ranking the top 10 space stories of the past year. One of those stories is that 2009 is the International Year of Astronomy. The year has had so many events marking this celebration that it’s hard to narrow down what I should write about. So what events did you find the most impressive? 100 Hours of Astronomy, which occurred back in April? The Earth to the Universe exhibit that could be seen at various non-traditional locations throughout the world?

What events did you attend? And what did you find made the most impact?

Picking the year’s top astronomy stories

Liz Kruesi — Thu, 27 Aug 2009 16:13:00 GMT

Each year Astronomy magazine publishes an article highlighting what we consider the top 10 astronomy stories of the previous year. I’ve started working on the article for 2009 and thought I’d share a few of our ideas for the big stories. We also want your feedback. So if there’s a story you feel strongly should be on our list, let us know!

Of course, the mission to repair the Hubble Space Telescope has to be on this list. Reviving the aging telescope (and possibly giving it another 5 years) is important not just to the field of astronomy, but public outreach.

The Jupiter collision is another big one. We hadn’t seen anything like that for 15 years. And it’s a great story of the amateur and professional community working together.

This past year the Fermi Gamma-ray Space Telescope released a slew of findings, including the most detailed gamma-ray map created. I’m a high-energy astronomy geek, so I just love this stuff.

And we can’t forget that 2009 was the International Year of Astronomy. It was an entire year devoted to reaching the general public and showing them just how awesome astronomy is.

Obviously I shared only four on this list ... we need to keep part of the article a surprise!

But we want your input, too. What do you think of these four? What stories do you think should be in our top 10 list?

Photo credit: NASA TV

New video: Dark matter explained

Liz Kruesi — Mon, 24 Aug 2009 18:11:00 GMT

In my newest video, I give you an overview of dark matter, that mysterious stuff that makes up some 90 percent of the universe’s mass. During the last few decades, astronomers have gained convincing evidence that stars, gas, and dust aren’t all there is to the universe. Most of it is “dark” — both dark matter and dark energy. This video focuses on dark matter, and it’s the second video in a series called “Cosmology 101.”

Also check out the video about the Big Bang.

Editor’s note: “Cosmology 101: Dark Matter” is available to registered members of Astronomy.com. Registration is free, so sign up today to watch this video and enjoy other great benefits.

Send us your astronomy questions

Liz Kruesi — Wed, 15 Jul 2009 21:05:00 GMT

Perplexed by planets? Confused by cosmology? Baffled by black holes? Then send in your questions to Astronomy magazine at askastro@astronomy.com.

If you have an astronomy question about observing, the planets, stars, cosmology, or astronomy history, send it in! Five are selected each month for publication in the Ask Astro section of Astronomy magazine. If your question is selected, we will forward it to an expert for his or her response. Then, the question and answer will appear together in a future issue. We may edit or revise your question for clarity.

We aren’t always able to respond to questions individually. But please keep the questions coming — they help us to learn what our readers are interested in, and what topics we should consider for future coverage in the magazine.

On the road: AAS meeting, Wednesday highlights

Liz Kruesi — Thu, 11 Jun 2009 14:18:00 GMT

Wednesday I had the time to attend most of the big talks (in addition to two press conferences). The first presentation of the morning was about astronomy education, public outreach, and Griffith Observatory in Los Angeles. I was planning on going to the observatory Wednesday night anyhow, so it definitely made me look forward to the visit.

Mike Brown, professor of planetary astronomy at the California Institute of Technology, gave the second talk of the day. He spoke about the outer solar system and a few minor planets (Sedna, “Snow White,” and Haumea). He also shared his thoughts on the Pluto debate — he believes Pluto is not a major planet. He was a dynamic speaker, and I really enjoyed the talk. Considering I’m usually not a solar-system astronomy person, that’s saying a lot! I learned quite a bit about the outermost objects in our solar system.

The last talk of the day focused on an exhibit at the Huntington Library just outside of Pasadena. After the presentation, I wished I had another day in California to visit the exhibit. It’s called “Beautiful Science: Ideas that Changed the World" and mostly showcases historical science books and manuscripts about astronomy, medicine, natural history, and light. It’s a permanent exhibit, so consider visiting it if you’re in the Los Angeles area.

After the conference ended for the day, I went out to Griffith Observatory. Recently the facility underwent a 4-year, $93 million renovation. It reopened in late 2006, so this was the first time I had seen it since the renovation. The exhibit halls have some great displays. Considering my interest in jewelry and beads, I especially enjoyed the timeline of the universe made with 2,200 pieces of celestial jewelry (image at right).

The planetarium show was great also. The night sky from a dark location is something that I rarely had the opportunity to see while growing up in Chicago, but the sight always makes me smile. There’s just something about seeing the Milky Way band stretching across the sky.

Griffith Observatory boasts many other interesting exhibits, from explaining Earth’s tides and different types of eclipses, to a fabulous display of the periodic table of elements, to a giant (the table showing the classification scheme of stars). In the picture to the right I’m pointing toward the Sun. Arcturus is the large yellow star above me. Betelgeuse is the red star in the upper right; however, Betelgeuse should have actually been 1.5 times the size of the room (as noted on the HR diagram). Exhibits such as this one really make you appreciate the scale of objects in the universe.

And so my trip to the 214th meeting of the American Astronomical Society has ended. I head back to Wisconsin Thursday, and I have to leave the hotel more than 4 hours before my flight in order to fight with Los Angeles traffic! Yes, the traffic is that bad.

Headlines from 214th meeting of the American Astronomical Society

Previous AAS meeting blog posts from Liz
Tuesday highlights
Monday highlights