This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Friday, July 15, 2022.
Information updated weekly or as needed.
Times given as local St. Louis time which is Central Daylight Time (CDT). For definitions of terminology used in the night sky update, click the highlighted text. If relying on times posted in Universal Time (UT), St. louis is -5 hours when CDT.
Public Telescope Viewings
Public telescope viewings at the McDonnell Planetarium have returned as part of the Saint Louis Science Center’s First Friday event. As we ease back into our telescope nights, they will operate a little different than before. To take part in our telescope viewings you will need to get a ticket for the planetarium show that starts at 7:00 p.m. as part of the First Friday event. Tickets for the First Friday planetarium show are free, but they can only be picked up at the Saint Louis Science Center on the night of the event. After the planetarium show ends you will be able to go outside and look through telescopes weather permitting. We will update this posting if anything changes.
Solar telescopes viewings have also returned and will take place every Sunday from 11:00 a.m. to 3:00 p.m. weather permitting. Solar Sundays will run from May 29, 2022, to September 4, 2022. The return of Solar Sundays is a good opportunity to prepare for the upcoming solar eclipses in 2023 and 2024.
Observing Highlight of the Week
The multiple star systems Epsilon Lyrae and Zubenelgenubi can be found at 10 pm this week. Image created using Stellarium.
Summer stars offer great targets for several reasons. Last week we explored the color of stars. This week we will look at a few multiple star systems. When looking at stars with the unaided eye, many you see are more than one star. Current estimates suggest that as many as 85% of stars we see are more than one star. Some are binary systems while some much larger multiple star systems. Multiple star systems are a great way to hone your skills in finding targets with binoculars or telescopes.
While tracking down multiple star systems, there are a few things to consider. You will need to find a sky atlas to help you identify star fields. When splitting these multiple systems, the brightest component is usually considered the primary star. The position of the additional component stars is measured with respect to the primary star’s location. The position angle (PA°) is an angular measurement with respect to the primary star. If you imagine a clock face surrounding the primary star, the PA° is measured in 360° with 0° at the top and 180° at the bottom. The degrees increase in a counterclockwise direction. The separation of stars in a system is posted in the degree, minute and second format. This is expressed as x° x’ x”.
If interested in viewing multiple stars, a great place to begin is with the Astronomical League’s Double star observing programs. There is one for binoculars and one for telescopes. These programs are useful for anyone as they contain lists of targets with relevant observing information.
The summer sky has several nice double stars to track down on these short nights. First, we will start with a star called Zubenelgenubi. This is the alpha star in the constellation Libra. This star is easy to spot naked eye even in the city lights of St. Louis. Start by looking for the constellation Scorpius in the southern sky. Scorpius appears as a bright fishhook shape low in the southern summer sky. Look east from the head of Scorpius and you will find three stars that look like the body of a coat hanger; this is Libra. Zubenelgenubi is the middle star of the three.
The primary star is magnitude 2.8 while the secondary is 5.2. The separation between the stars is close to 4’. This double will be easily split by any binocular. When I last saw the pair, they looked yellow to me.
The other double I would recommend is known as the Double-Double in Lyra. Officially named Epsilon Lyrae, it is known as the Double-Double because it is not just two stars but rather is four. If viewed through binoculars, Epsilon Lyrae will look like two bright stars. If using a telescope at 100x magnification, you should be able to see all four stars of this system.
The four stars of Epsilon Lyrae are arranged into two pairs. Each pair consists of two stars that orbit one another while both pairs also orbit each other. The two pairs have a separation of roughly 3’.
Not all double stars are true physical pairs. Some fall into the category of line-of-sight doubles. Alpha Capricorni and Omicron Cygni are two good examples. While not true double stars, these line-of-sight doubles are naked eye targets. Multiple star systems may not be of interest to all, but they offer something to track down on these short summer nights.
The Sun and Moon
The Moon as seen from the International Space Station, on July 31, 2011.
Credit: NASA
Sunrise is at 5:49 a.m. on Friday, July 15 and sunset is at 8:25 p.m. providing us with roughly 14.5 hours of daylight. Even after sunset, the light from the Sun will dimly illuminate our sky for just under 2 hours. This period is called twilight, which ends around 10:17 p.m. this week. For those with a sundial, local noon occurs around 1:06 p.m. this week.
| Day | Sunrise | Sunset |
|---|---|---|
| 2022-07-15 | 5:49 a.m. | 8:25 p.m. |
| 2022-07-16 | 5:49 a.m. | 8:24 p.m. |
| 2022-07-17 | 5:50 a.m. | 8:23 p.m. |
| 2022-07-18 | 5:51 a.m. | 8:23 p.m. |
| 2022-07-19 | 5:52 a.m. | 8:22 p.m. |
| 2022-07-20 | 5:52 a.m. | 8:21 p.m. |
| 2022-07-21 | 5:53 a.m. | 8:21 p.m. |
| 2022-07-22 | 5:54 a.m. | 8:20 p.m. |
| 2022-07-23 | 5:55 a.m. | 8:19 p.m. |
Moon
Moonrise for Friday, July 15 occurs at 10:28 p.m. and moonset will occur at 9:02 a.m. on the following day. On Friday, July 15, the Moon will exhibit a waning gibbous phase with 94% of the lunar disk illuminated. Last quarter moon occurs on July 20, 2022, at 9:19 a.m.
International Space Station (ISS) Observing
There are numerous passes of ISS visible from St. Louis for the week of July 15. They occur during morning and evening hours. The table below lists the best passes visible from St. Louis this week.
Catch ISS from St. Louis starting Friday, July 15
| Date | Starts | Max. altitude | Ends | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Time | Alt. | Az. | Time | Alt. | Az. | Time | Alt. | Az. | ||
| 17 Jul | -1.8 | 20:52:13 | 10 | W | 20:55:16 | 33 | NNW | 20:58:20 | 10 | NE |
| 18 Jul | -0.6 | 21:42:28 | 10 | NW | 21:44:10 | 13 | NNW | 21:45:52 | 10 | NNE |
| 19 Jul | -0.5 | 00:57:31 | 10 | NNW | 00:58:12 | 13 | NNW | 00:58:12 | 13 | NNW |
| 19 Jul | -0.8 | 20:53:15 | 10 | WNW | 20:55:31 | 17 | NNW | 20:57:49 | 10 | NNE |
| 22 Jul | -0.7 | 00:08:47 | 10 | NNW | 00:09:45 | 16 | NNW | 00:09:45 | 16 | NNW |
| 22 Jul | -1.2 | 23:20:38 | 10 | NNW | 23:22:46 | 18 | NNE | 23:22:46 | 18 | NNE |
| 23 Jul | -1 | 22:32:31 | 10 | NNW | 22:34:19 | 14 | NNE | 22:35:48 | 11 | NE |
Magnitude (Mag): The Measure of brightness for a celestial object. The lower the value is, the brighter the object will be.
Altitude (Alt): The angle of a celestial object measured upwards from the observer’s horizon.
Azimuth (Az): The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.
For information about ISS flyovers and other visible satellites, visit www.heavens-above.com
Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:
The Visible Planets
Looking southeast at 5:00 a.m. July 18, 2022. Credit: Stellarium, EG
This week, four naked eye planets are visible. Venus, and Mars are best seen before sunrise in the east and southeast. Jupiter and Saturn are now rising before midnight and will be good targets by 1:00 a.m. in the southeastern and southern sky.
Venus
Venus has started a morning apparition and will be seen in the southeast before sunrise. Venus rises at 3:57 a.m. and should be easy to spot in the southeast by 5:00 a.m. The current morning apparition lasts until the third week of October 2022. Venus reaches superior conjunction on October 22, 2022.
Mars
Mars rises at 1:05 a.m. Start looking for the red planet around 2:00 a.m. as it clears trees and buildings. Mars will continue to climb out of the Sun’s glare as it heads towards opposition later this year on December 7, 2022.
Jupiter
Jupiter rises at 11:43 p.m. and should be visible by 12:45 a.m. As the year goes on, Jupiter will rise about 25 minutes earlier than it did the week before. Jupiter will reach opposition on September 26, 2022, so our best views of this giant world will come at the end of summer and through the fall months.
Saturn
This week Saturn will rise around 9:52 p.m. Start looking for Saturn around 11:00 p.m. in the southeastern sky. Saturn will reach opposition on August 14, 2022. As we head to this date, Saturn will rise earlier each day.
James S. McDonnell Planetarium
Night Sky Update: July 15 – July 23, 2022