jump to navigation

Observatory OPEN House Tonight!! October 31, 2008

Posted by jcconwell in Astronomy.
add a comment

Look for pumpkins ringing the observatory, and more than a few mad scientists. The fun starts at 8:00PM

Advertisements

Hubble Back Online! October 30, 2008

Posted by jcconwell in Astronomy, telescopes.
add a comment

From the NASA news Center:

NASA’s Hubble Space Telescope is back in business. Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of gravitationally interacting galaxies called Arp 147. The image demonstrated that the camera is working exactly as it was before going offline, thereby scoring a “perfect 10” both for performance and beauty.

The two galaxies happen to be oriented so that they appear to mark the number 10. The left-most galaxy, or the “one” in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation. The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, and it is more than 400 million light-years away from

Galaxies, planets, black holes and Angular momentum October 21, 2008

Posted by jcconwell in Astronomy, physics.
Tags: , , , ,
add a comment

I was originally going to make this blog about black holes and jets, as part of a multi-part series on black holes in general. It began when a friend asked me how can jets come from black holes and also why spiral galaxies are flat? They both have a common concept that appears over and over in astrophysics, and ice skaters…

Conservation of angular momentum.

Conservation laws are very useful to understand what’s going on in a system. Charge, mass, energy, linear momentum, and today’s topic, angular momentum, are all conserved in an isolated system.

If a quantity is conserved, it means it’s unchanged. Look at it before or after, and it’s the same.

Angular momentum is like linear momentum, it says an isolated body in motion will remain in motion, only this concept talks about rotational motion. Now angular momentum depends on 3 things, how fast is the rotation, how much mass there is, and the final, the sneaky one, the distribution of the mass, or how far away the mass is from the axis of rotation.

so the angular momentum L ~ (mass)(rotation)(distance of mass from axis)2

Why the third quantity is squared goes into more physics than needed here.

You can see the dependence on the third factor , “distance of mass from axis” , with an ice skater. When she completes her routine, she starts a slow rotation, then she brings in her arm and spins up. As she brings in the mass of her arms, the third quantity goes down, so for L to be constant (conserved), the rotation MUST increase.

Now most astronomical objects, stars , planets, galaxies are formed from big balls of gas.

This gas has some small random rotation. As the gas contracts, due to its gravity, it starts to spin up faster. Because it’s a fluid (think of spinning a ball of jello on a toothpick ) as it spins up it flattens out along its equator. If you look at pictures of Jupiter, which spins 3 times faster than Earth, you’ll see it’s an ellipse not a sphere. During the creation of a star, some of the mass of the gas cloud that forms the star rotates so fast it flattens out into a pancake, or disk, and may begins to form planets. Which is why it’s thought all the planets orbit in the same direction and almost in the same plane in our solar system. The same process occurs to form accretion disks around black holes and neutron stars.

Some think a spiral galaxy is thought to be just a scaled up version of this disk formation.

Now for the giant elliptical galaxies, these are thought to form out of galaxy collisions. which strip them of gas, and after the merger of several galaxies the angular momentum/mass is reduced because the rotations of the individual galaxies are random, some left, right, some up, some down, for a large collection of galaxies. This leaves a much rounder looking object.

The formation of galaxies is an ongoing area of research. There is still much debate and the details may change. In a few years the large infrared telescopes like the Spitzer space telescope, and Hubble’s successor the James Webb space telescope will be able to see the formation of galaxies within the first billion years after the big bang, and give new insights into these processes.

Meteor Update. October 14, 2008

Posted by jcconwell in Asteroid, Astronomy.
Tags: ,
add a comment

The asteroid that was predicted to hit Earth over the Sudan last week did have a Kodak moment . A weather satellite, METROSAT-8, was lucky enough to catch the fireball (from above!) as it was burning up in the atmosphere. For more information, go the the EUMETSAT site

Fireball over Northern Sudan

Fireball over Northern Sudan

Weird planet October 13, 2008

Posted by jcconwell in Astronomy, planets.
Tags: ,
add a comment

COROT is a mission led by the French Space Agency, with contributions from ESA, Austria, Belgium, Germany, Spain and Brazil. Launched in December 2006, It carries a 27-cm aperture (10.5 inch) telescope designed to detect tiny changes in brightness from nearby stars. The mission’s main objectives are to search for exoplanets and to study stellar interiors. COROT has discovered a massive planet-sized object orbiting its parent star closely, unlike anything ever spotted before. It is so weird, that scientists are unsure as to whether this object is a planet or a failed star.

Called COROT-exo-3b, it is the size of Jupiter, but has over 20 times Jupiter’s mass. This would make a planet that has twice the density of lead

Credit OAMP

Credit OAMP

COROT-exo-3b was discovered by a drop in the brightness of the star each time the object (COROT-exo-3b) passed in front of the parent star. For more information go to the European Space Agency

Update: Impact of Asteroid 2008 TC3 Confirmed! October 8, 2008

Posted by jcconwell in Asteroid, Astronomy.
Tags: ,
add a comment

A bright fireball was observed and sonic sensors registered a upper atomsphere explosion in the range of 1000 tons of TNT over northern Sudan. For more information check out the NASA NEO news.

http://neo.jpl.nasa.gov/news/news159.html

http://neo.jpl.nasa.gov/news/news160.html

Asteroid to Burn Up Tonight! October 7, 2008

Posted by jcconwell in Asteroid, Astronomy.
Tags: ,
add a comment

Just to the right of center, in the picture below, you will see a small dot. This is asteroid 2008 TC3. It’s about the size of a small car and was first discovered on Monday by the telescopes at Mt Lemon. The asteroid moves quick compared to the background stars, so when the telescope is fixed on the asteroid for a long exposure the stars will appear as streaks.

It is expected to hit in Northern Sudan in the evening. It holds the distinction of being the first asteroid to have a have a predicted impact on the Earth. It is between 2 to 5 meters in length and is expected to burn up in the upper atmosphere, creating a nice fireball. But if in the higher end of the size range, small fragments, about the size of your fist, may survive the burn up.

P. Scott Smith has an Asteroid named after him! October 3, 2008

Posted by jcconwell in Asteroid, Astronomy.
Tags: ,
add a comment

I’ve known P. Scott since I’ve my arrival at Eastern in 1985. He retired in 1988 from the physics faculty. He’s one of the major reasons EIU’s observatory is such a success. So when one of his students Dr. Robert Millis, the director of Lowell observatory discovered an asteroid and named it after him I couldn’t think of a finer tribute.

Full story at http://www.eiu.edu/~pubaff/headline/2008/0707200890.php

Busy September, and a new record! October 2, 2008

Posted by jcconwell in Astronomy, IYA 2009, Observatory.
Tags: , ,
add a comment

Wow!!! Once a professor start teaching courses time goes by too fast..But the real reason I haven’t been talking about astronomy in cyberspace is I’ve been too busy talking to people in real space.

I was just looking at the count of visitors to the observatory. The total count for the month of September is 426, a new record for the month. The single night record is still the Mars observation from 2 years ago at 350. I’m not even adding in the three visits to schools this month.

The nice thing is about 1/2 the visitors are school age, K through 12. The smallest age group is college students. Friday nights are great for families, but most college students have other plans and many now go home for weekends.

The next public open house is on October 31. We traditionally ring the observatory with Jack-O-Lanterns, and for this date we may even have a few ghosts.

And perhaps a mad scientist, most people can’t tell the difference anyway….it’s OK ….I have tenure.