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This coming week is going to offer some beautiful sights in the night sky. On Monday evening, August 11, a rises about 25 minutes before Saturn on the right (west) side of Pisces. Saturn will become visible above the eastern horizon about 10:10 p.m. (when Saturn is about 5 degrees above a perfectly flat horizon). At that time, Saturn will be to the lower left of the moon. The moon will wash out the dim stars of Pisces but you should still be able to pick out the stars of the to the upper left of the moon. The moon and Saturn should fit within the same field of view of binoculars.

As the night progresses, the Great Square of Pegasus, Saturn, and the moon will arc together across the sky but the moon will drift closer to Saturn. By 6 a.m. on August 12 (15 minutes before sunrise), they will be in the southwest and the moon will be just 3.5 degrees from Saturn. 

More spectacular that early morning (August 12) will be the close conjunction of the two brightest planets, Venus and Jupiter. They will be less than a degree apart (a thumb-width at arm鈥檚 length) as they rise a few minutes before 4 a.m. in the middle of Gemini. At the scale of the attached star chart, they seem to merge! Jupiter will be the dimmer of the two, positioned to the upper left of Venus. Although they will have another conjunction in about a year (June 2026), it won鈥檛 be as good as Tuesday morning鈥檚 view. It won鈥檛 be until November 2028 when they have another close conjunction, so set your alarm to take a look before the sun rises!

The following night (August 12/13) is the peak of the famous . The bright waning gibbous moon is going to dampen the display a bit, though. Instead of the 50-75 meteors per hour that can be visible on a dark sky far from the city, we鈥檒l probably just see at most 20 meteors per hour. In the evening of August 12 before the moon rises (before 10:15 p.m.), the Perseid radiant will be low in the northeast. At this time, you can see the 鈥渆arthgrazers鈥�, dust bits that hit the atmosphere tangentially to produce long trails.

The Perseids are the result of Earth plowing through the . The comet dust bits, about the size of a tiny grain of sand, hit the atmosphere at 37 miles/sec, burning up many tens of miles above the ground. The combination of Earth鈥檚 direction of motion in August and the inclination (tilt) of the comet鈥檚 orbit with respect to Earth鈥檚 orbit makes the meteors appear to shoot outward from a radiant that is in the upper left part of Perseus. The radiant will be up higher in the pre-dawn hours but because of the bright moon this year, you鈥檒l want to face north鈥攁way from the moon to keep your eyes dark-adapted. Venus and Jupiter will still be quite close together on the morning of August 13, so you can enjoy that sight while you watch for meteors! The Swift-Tuttle dust trail is a bit puffy, so the Perseids are active from as early as July 17 to as late as August 23.

In Earth science news, the that is a collaboration of NASA and the Indian Space Research Organisation (ISRO) . Using the most advanced ever put in orbit, NISAR will be able to detect the movement of land and ice surfaces down to one centimeter. This will help us understand processes in natural hazards such as ; weather disasters such as ; changes in ; and how affect the cycling of carbon in Earth鈥檚 climate. 

NISAR will pass over the same locations every 6 days, so we can see how surface features, moisture content, surface roughness, and motion have changed over time. The radar can see through clouds and light rain and works day and night. Spaceborne synthetic aperture radar systems have been used for Earth science observations since 1978, so with ever-increasing capabilities. With the great resolution of NISAR鈥檚 radar system, comes a huge data stream鈥攁bout 80 terabytes of data per day will be generated for anyone to use free of charge. Both NASA and ISRO will manage satellite operations.

Space science missions take many years to develop. NISAR鈥檚 development began in 2014 and construction began in 2021. Integration and testing of the two radars in the system took another two years, followed by another couple of years of integrating the system to the spacecraft bus. The large cuts in the NASA workforce () mean that there will be no new science satellites from the USA after the current construction pipeline runs out over the next two-three years. Although , the damage is already done. 

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Director of the William M Thomas Planetarium at 51成人动漫

Author of the award-winning website