Fakulta matematiky, fyziky
a informatiky
Univerzita Komenského v Bratislave

Mgr. Adrián Galád, PhD.

An astronomer interested in asteroids, keen on their observations to recognize unknown.

He offers an optional basic course "Asteroids" for students interested in astronomy.

Since 1994 he has used an old 0.60-m telescope of the Faculty of Mathematics, Physics, and Informatics, Comenius University, Bratislava, Slovakia. It is located near Modra, within 40 km of Bratislava. He is thankful for the opportunity which helped him use successfully even larger telescopes, namely 1.0-m Swope in Las Campanas Observatory, and 1.5-m Danish in European Southern Observatory at La Silla, both in Chile. Despite of the fact that only a limited observing time was awarded there, it was inspiring and unforgettable experience for him.

His observations led not only to a few asteroid discoveries or codiscoveries, or to better determination of orbit for hundreds of objects, but contributed also to finding out some of their physical properties, such as rotation period, size, shape, pole position, binarity, mass, bulk density, surface composition, spinning up or even splitting. His research has been supported not only by Comenius University, but since 2004 significantly also by Academy of Sciences of the Czech Republic.

In general, he considers asteroids as friends, though part of them are dangerous for life. For example, one of his discoveries belongs to a group of threatening asteroids, though its size is only ~ 25 - 30 m. Just imagine! If that body passing by within 1 035 000 km (2.7 times lunar distances) was on a collision course with Earth, it would release energy ~ 30 - 40 times larger than a bomb that was dropped on Hiroshima in 1945. Encounter velocity was ~ 12 km/s, but the estimate of energy is crude due to assumed asteroid size and unknown composition (bulk density). In addition to that, just several hours since discovery would be at disposal to compute the impact site (which would probably be crude estimate at most) and, in case it is a populated area, inform people there in time to evacuate if needed. And now imagine that larger bodies and objects with large density are also out there, while even larger encounter velocity is possible... 


Here, threatening asteroids are those that can collide with Earth and that are also big enough to pass through the atmosphere (size >~10 m). There are several million bodies of that size that "cross" the Earth's orbit (in two dimensional space). Only several thousands of them have known orbits. It is still not possible to detect all small bodies in the foreseeable future with current technique. By 2020 current and future powerful survey telescopes aim to discover most of medium-sized threatening asteroids (>150 m in size) (assuming corresponding funds are available).

Collisions with threatening bodies always occur at large encounter velocity (>11 km/s). Large asteroid impacts the Earth rarely, but when it happens, it is connected with devastating consequences for the whole biosphere (~two collisions in 1 million years with bodies larger than 1 km in size; nearly all such large bodies are known and no one is known to pose any danger in the upcoming years). On the contrary, collisions with small bodies are quite frequent (one collision with 10 m body in several years), though with only local importance to the biosphere, if any. But it should be mentioned that even tiny meteorites (usually remnants from small asteroids that survived passage through the atmosphere) provide valuable information about asteroid composition and history of the Solar System. 

Interesting, isn't it? So, let's study also these bodies (both asteroids and meteorites). We all may be better prepared when one of potential killers is recognized in advance to be on a collision course with us.   


official: galad(at)fmph.uniba.sk 


unofficial (private)adriangalad(at)yahoo.com (most frequently used - though it was out of my control, when stollen by someone on Sep 15, 2009 for one day. My apology for the things that happened to people in my contact list at that time.)

                            agalad(at)zoznam.sk (if previous fails)

                            agalad(at)pobox.sk (in the past, not used any more)