Spring 2015 - Volume 44, Number 2
Table of Contents
[19] Changing the Textbooks: Classic Early Achievements of the HST, Jennifer Wiseman
From amazing discoveries to iconic images, Hubble has impacted both science and culture.
[25] New Frontiers: Hubble’s Unexpected Accomplishments, Kenneth Sembach
A new telescope usually means unexpected discoveries, and the HST was no exception.
[31] The National Parks and the Milky Way, Tyler Nordgren
We have lost sight of our home in the universe, except in our National Parks.
[37] Astronomy in the News
Aurora on Ganymede suggests an underwater ocean, a cloudy superworld with a chance of more clouds, and phantom objects near dead quasars. These are some of the HST discoveries that recently made news in the astronomical community.
Departments
[4] Perspectives, Paul Deans
A Quarter Century of Science
[5] First Word, Linda Shore
An Astronomical Revolution
[7] Annals of Astronomy, Clifford J. Cunningham
The Comet of 1018
[8] Astronomer’s Notebook, Jennifer Birriel
The Curious Case of the Missing Sunspots
[10] Planetary Perspectives, Emily Joseph
Hubble and the Solar System
[11] Strange New Worlds, Courtney Dressing
Making Other Earths
[13] Armchair Astrophysics, Christopher Wanjek
Dark Matter Reveals Its Hands-Off Personality
[14] Education Matters, Brian Kruse
Analogous Shifts: NGSS and the HST
[16] Reaching Out, Bethany Cobb
Collective Gasps
[17] Societal Impact, Paul Deans
More Things Hubble
[47] ASP Tidings
Welcome New Members
[48] Sky Sights, Paul Deans
Venus and Jupiter Dance at Dusk
[51] Reflections, STScI
Hubble Ultra Deep Field
Changing the Textbooks: Classic Early Achievements of the HST
by Jennifer Wiseman
This is a great year for Hubble. Almost every year is a great year for Hubble. But this being the 25th anniversary, we’re particularly excited to talk about not only what has been accomplished with Hubble but also what is being accomplished and what will be accomplished, because the HST right now is as scientifically powerful as ever!
As we look back to the early years, we ask ourselves: why a space telescope? There have been many explorations into that question, so I won’t try to play historian — but I’ll give you a couple of tidbits….The first announcement of opportunity was put forth in 1977, listing ideas for science instrument teams and instrument proposals and for participation in the mission in other ways by scientists. That announcement included more than 20 examples of the kinds of science you might be able to do, uniquely from space, if you had this kind of capability.
New Frontiers: Hubble’s Unexpected Accomplishments
by Kenneth Sembach
There probably aren’t enough hours in the day to tell you what we’ve been surprised by with Hubble. So I’m going to give you a little bit of a whirlwind tour of the some of them. Hubble was designed to do a lot of different things, and many of the great things that it has done weren’t even envisioned at the time it was thought about — or launched. A good example of this is exoplanets; the first exoplanet wasn’t confirmed until 1992, after the Hubble launch.
The same comments could be made about…different topics — whether it’s the ages of stars or black holes or dark energy or gamma ray bursts. Hubble has touched all areas of astronomy and made discoveries in all of them. I’m going to describe a couple of these areas that you may be familiar with, because they’ve been in the news a lot in the last few years. So let’s talk about dark energy.
The National Parks and the Milky Way
by Tyler Nordgren
In 2005, I had a moment that changed my life. I had just received tenure, and I celebrated by going to a National Park. While I was there, I did what many park visitors do. I took in a Ranger program, which happened to be about astronomy. I thought well, that’s great — I’m an astronomer and I love astronomy. It was in an outdoor amphitheater under beautiful clear skies, and as it got dark that night, the stars came out — as did the Milky Way.
As the Ranger spoke about all the amazing things that visitors can see in the National Parks, people began to ooh and aah. I realized that I was sitting there with 100 people who were probably seeing the Milky Way for the very first time. I had seen it at various observatories around the world, and so while it wasn’t exactly ‘old hat’ for me, it was something that I had, in fact, taken for granted.
So it has come to this. The Milky Way is something you have to travel to see. You have to make that effort. But in the case of the National Parks, the night sky is something we still have, almost by accident.
Hubble Finds Phantom Objects Near Dead Quasars
Space Telescope Science Institute
NASA’s HST has photographed a set of wispy, goblin-green objects that are the ephemeral ghosts of quasars that flickered to life and then faded. The glowing structures have looping, helical, and braided shapes. “They don’t fit a single pattern,” said Bill Keel of the University of Alabama, Tuscaloosa, who initiated the Hubble survey. Keel believes the features offer insights into the puzzling behavior of galaxies with energetic cores.
The ethereal wisps outside the host galaxy are believed to have been illuminated by powerful ultraviolet radiation from a supermassive black hole at the core of the host galaxy. The most active of these galaxy cores are called quasars, where infalling material is heated to a point where a brilliant searchlight shines into deep space. The beam is produced by a disk of glowing, superheated gas encircling the black hole.
“However, the quasars are not bright enough now to account for what we’re seeing; this is a record of something that happened in the past,” Keel said. “The glowing filaments are telling us that the quasars were once emitting more energy, or they are changing very rapidly, which they were not supposed to do.”
Keel said that one possible explanation is that pairs of co-orbiting black holes are powering the quasars, and this could change their brightness, like using the dimmer switch on a chandelier.
The green filaments are believed to be long tails of gas pulled apart like taffy under gravitational forces resulting from a merger of two galaxies. Rather than being blasted out of the quasar’s black hole, these immense structures, tens of thousands of light-years long, are slowly orbiting their host galaxy long after the merger was completed.
