By Dave Grosvold
You can spot 1 Ceres
any night this week as it moves through the constellation Ophiuchus
(pronounced Oh-FEE-eh-kuss) with binoculars or a small scope. Ceres, the largest astronomical body in the asteroid belt, was discovered on Jan 1, 1801 by Giuseppe_Piazzi
. After having been designated as a planet in 1801, Ceres enjoyed that elevated status for only a short time, until a number of other small objects were discovered in the space between Jupiter and Mars. In 1802, William Herschel
coined the term asteroid
("star-like") to refer to these small bodies — bodies that were too much like stars to be planets, but wandered in the same way.
Ceres was reclassified as a dwarf planet
after the status of Pluto was debated and demoted in 2006. Ceres is now the smallest dwarf planet in the Solar System, rather than the largest asteroid, but remains designated formally as 1 Ceres since it was the first such body to be discovered. 1 Ceres is currently still as bright as magnitude 7.3, and can be located by using the finder chart
. The best way to distinguish Ceres from the background stars is to observe it on several different nights. The obvious movement from night to night compared to the background will give it away.
Some very bright Iridium Flares
may be visible this week! On Wednesday evening, June 30th, Iridium 26
will flare to a magnitude of -3.0 in the WSW at 11:36 PM CDT. Look for it at an altitude of 19° above the horizon. Any time we refer to magnitude in this article, we are actually referring to apparent magnitude
, which is how the brightness of an object appears to observers on Earth, as opposed to its intrinsic brightness, or absolute magnitude
In the early morning hours of Thursday, July 1st, you may be able to catch Iridium 12
flaring to a very bright magnitude -7.0 at 4:16 AM CDT, 27° above the horizon in the ESE. Iridium 23
also flares to a brilliant -7.0 magnitude on Thursday evening at 11:30 PM CDT. Look for it at an altitude of 19° in the WSW. A magnitude of -7.0 is several orders of magnitude brighter than Venus at its brightest! Venus only reaches -4.67 when it is in it s crescent phase and closest to Earth. So these flares will be very bright.
Another pair of bright Iridium Flares appropriately occur on Independence Day
, Sunday, July 4th. At 4:04 AM CDT in the ESE, look for Iridium 91
at 23° above the horizon, flaring to a -4.0 magnitude. Again at 11:21 PM in the WSW, Iridium 22
hits magnitude -6.0 at altitude 18°.
Finally, look for Iridium 56
and Iridium 41
in the early morning on Tuesday, July 6th flaring to -5.0 and -7.0 in the SE at 28° and the E at 12° respectively. Iridium 56
will flare at 3:54 AM CDT and Iridium 41 at 5:14 AM, CDT.
The International Space Station
(ISS) makes only one pass low in the NNW this week, starting at 11;56 PM CDT on Monday, July 5th. The ISS starts at altitude 10° in the NNW, then barely swings up to a maximum altitude of 11° in the NNW, and quickly fades from view. The ISS will only reach a maximum brightness of magnitude 0.0, or just slightly brighter than Vega
in the constellation Lyra
at magnitude 0.03.
closes in on Regulus
in the constellation Leo
day by day, while Mars
closes in on Saturn
. The diagonal line of Saturn, Mars, Regulus, and Venus is shrinking every day. The three planets will be very close together low in the west at sunset by early August. A telescope shows Saturn's Rings
a mere 2° from edge-on right now, but the rings will continue to increase their tilt with respect to Earth over the next 15 years.
The waning gibbous Moon
rises around midnight on Friday, July 2nd, and about 45 minutes later, Jupiter
rises beneath it. Jupiter is slowly working its way back into the evening sky, and should be a bright Evening Star
by mid-autumn, while Venus
sinks into the glare of the autumn sunset
As night falls this time of year, look for red Arcturus
high in the southwest straight above Spica
in the constellation Virgo
. The kite shape of the rest of the constellation Boötes
extends straight up from Arcturus. By the way, Boötes is pronounced "Bo-OH-teez" or "Bo-OH-tiss," not "BEWT-eez", as some might assume. Pronunciation of constellation names is open to debate, but there are several accepted pronunciations for most constellations. If you're interested, See the Sky & Telescope
magazine web site for a Pronunciation Guide