Shower of dust and rockets

The Lyrid meteors should be seen in the nights of April 21, 22, and 23. A  few Lyrids can be in the sky all the way from April 14 to 30, but the predicted peak this year is April 22 around 19h Universal Time, which is 4 or more hours earlier by North American clocks.

Here is the radiant climbing into view over the north-eastern horizon.

See the end note about enlarging illustrations.

The radiant of a meteor shower is the point or small area from which the “shooting stars” appear to fly out into all parts of the sky. They are really traveling in parallel tracks, being particles that separated, perhaps centuries ago, from a comet. In this case it was comet C/1861 Thatcher, which was seen only in 1861, but appeared to be in an elliptical orbit with a period of 415 years.

The radiant is near the brilliant star Vega, in the constellation Lyra, though it shifts slightly from night to night (as shown by the arrow we’ve drawn through it) because, as Earth travels on around its own curved orbit, the angle changes at which it intersects the meteors’ orbit. As the night goes on, the radiant climbs higher (as shown by the broad arrow on the celestial equator), and is highest in the after-midnight hours, as happens with many meteor showers.

The Moon, traveling south of the ecliptic and approaching its last-quarter position, will rise not long after midnight. As it climbs higher, it may somewhat interfere with meteor-spotting, though it is less than half as bright as when it is full.

In this space view from ecliptic north, America is coming around into view of the meteors. The  Moon is about in the same direction as the meteor radiant in longitude, but it is more than 35° south of it.

The Lyrid shower is about the year’s 6th strongest, judging by its ZHR or zenithal hourly rate, which is estimated at 18. (Compare 120 for the Quadrantids of January, and 150 for the Geminids of December.) But the ZHR is a provisional guide: the number of meteors that might be counted in one hour at the peak time by a single observer, if the sky is clear and dark – and the radiant is overhead, which it isn’t except along latitude 34° north. So the actual number you count is likely to be less.  – But it could be more: meteor streams, like the comets from which they are born, are fuzzy beasts and delight in defying predictions!

Colling with Earth almost head-on, these meteors can be bright enough to be called fireballs or bolides, and many of them leave trails.

Bolides down on Earth

Russia’s war on its smaller neighbor and former satellite Ukraine is inflicted mainly by cowardly long-distance bombardment with air-strikes, rockets, and shells, indiscriminately “softening up” not just military targets but civilians’ houses and hospitals and churches and farms and lives, now as far west as Lviv on the Polish border, where thousands of refugees are trying to escape. And now five-ton bombs are to be dropped on the steel factory in Mariupol.

For seven weeks, brave outnumbered marines have been holding out against the complete capture of this port city, essential to Ukraine – from it 12 percent of the world’s wheat is exported – and coveted by Russia so as to grab most of Ukraine’s coast and link up with the Crimea illegally conquered in 2014. Most of Mariupol has been pulverized and more than 21,000 of its civilians killed, and the defenders, outnumbered ten to one, driven street by street into a fragment of the center, are holding out in the great factory with its complex of basements. They have refused the deadline to surrender. But they have no supply of ammunition, or food.

I wish a NATO country would send a warship in through the strait into the Sea of Azov and either evacuate, or re-supply, as they choose, those heroes.

__________

ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image” or “Open image in new tabV, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

Sometimes I make improvements or corrections to a post after publishing  it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.  Or you can click ‘Refresh’ to get the latest version.

This weblog maintains its right to be about astronomy or anything under the sun.