The constellations Orion, Gemini and Taurus rise earlier each morning in the eastern predawn sky. When I see this, I cannot help but think “Winter is coming.”
The constellation Orion in the predawn sky to the east on Aug. 21, 2018. Credit: Stellarium / Bob Trembley.The southern sky continues to have a beautiful splash of planets, and will make for good observing this week; deep-sky objects may be washed-out by the nearly full Moon, which will be visible almost all night this week.
The Moon, Saturn and Jupiter in the south-southwestern sky shortly after 10:00 PM, Aug. 21 2018. Credit: Stellarium / Bob Trembley.Mars and Saturn are high in the southern sky at midnight, the Moon joining them between August 22-24.
The Moon, Mars and Saturn in the southern sky at midnight, Aug. 22 2018. Credit: Stellarium / Bob Trembley.Jupiter moves slowly westward towards Venus, as Venus appears lower in the southwestern sky each evening.
Jupiter and Venus in the southwestern sky at dusk, Aug. 21, 2018. Credit: Stellarium / Bob Trembley.Southern Hemisphere:
From Cape Town, South Africa the splash of planets that appear on my southern horizon are nearly directly overhead at 8:00 PM.
Overhead at 8:00 PM from Cape Town, South Africa, Aug. 21, 2018. Credit: Stellarium / Bob Trembley.The Moon
The Moon is a waxing gibbous heading towards full on August 26th. Afterwards the Moon will be a waning gibbous.
The Moon from Aug. 21-27, 2018. Visualizations by Ernie WrightThe Moon may or may not be a good observing target this week – the fires across the west have spread haze across the U.S. and Canada; if you can see the Moon, it may have an odd orange-red hue to it.
Observing Target: The Garnet Star
From Wikipedia:
“Mu Cephei (μ Cep, μ Cephei), also known as Herschel’s Garnet Star, is a red supergiant star in the constellation Cepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as the M2 Ia standard by which other stars are classified.
Mu Cephei is visually nearly 100,000 times brighter than the Sun, with an absolute visible magnitude of Mv = −7.6. Summing radiation at all wavelengths gives a luminosity of around 283,000 L☉ (bolometric magnitude −8.8), making it one of the most luminous red supergiants in the Milky Way. It is also one of the largest known stars with an estimated radius over 1,000 times that of the sun (R☉), and were it placed in the Sun’s position it would reach between the orbit of Jupiter and Saturn.”
Herschel’s Garnet Star. Credit: Flamsteed Astronomical SocietyI saw the Garnet Star from the Warren Astronomical Society’s Stargate Observatory – it’s red color is quite striking!
Location of Herschel’s Garnet Star. Credit: Stellarium / Bob Trembley.The Sun
The Sun has a spot! A very small spot, hard to see spot, but enough to reset the “spotless days” counter. You can see sunspot AR2719’s location in the animation below – rotating towards the center of the Sun’s disk with a small amount of coronal loop activity.
The northern coronal hole has another long tendril stretching down past the equator. A hole has re-formed at the south pole, and there is a relatively large couple of holes near the equator. The solar wind speed is 603.9 km/sec, with a density of 4.3 protons/cm3. (That’s pretty darn fast!)
SpaceWeather.com says: “A stream of high-speed solar wind is buffeting Earth’s magnetic field, sparking bright auroras around the Arctic Circle. The gaseous material is flowing from a wide hole in the sun’s atmosphere–so wide that Earth could remain inside the stream for days to come. NOAA forecasters estimate 50% chance of polar geomagnetic unrest on Aug.21st.”
A couple medium-sized prominences appeared on the Sun for last couple days… I would have loved to show them on Sunday at the Michigan ComicCon, but the skies were uncooperative all weekend. AR2719 appears as the bright orange region on the left of the animation below.
You can create your own time-lapse movies of the Sun here: AIA/HMI Browse Data.
You can browse all the SDO images of the Sun from 2010 to the present here: Browse SDO archive.
STEVEs
While I was at SpaceWeather.com this morning, I saw a post there about “STEVEs” – they’re NOT aurora!
“Our results verify that this STEVE event is clearly distinct from the aurora borealis since it is characterized by the absence of particle precipitation,” say the researchers. “Interestingly, its skyglow could be generated by a new and fundamentally different mechanism in Earth’s ionosphere.”
I’ll post more about these after I’ve read a couple research papers: “On the Origin of STEVE: Particle Precipitation or Ionospheric Skyglow?” and “New science in plain sight: Citizen scientists lead to the discovery of optical structure in the upper atmosphere.”
“Steve.” Taken by Greg Ash on May 5, 2018 @ Ely, MnAsteroids
Upcoming Earth-asteroid encounters:
| Asteroid |
Date(UT)
|
Miss Distance
|
Velocity (km/s)
|
Diameter (m)
|
| 2018 PN20 |
2018-Aug-15
|
15.3 LD
|
11.4
|
32
|
| 2018 PY23 |
2018-Aug-15
|
1.3 LD
|
25.1
|
9
|
| 2018 PM20 |
2018-Aug-16
|
8 LD
|
9
|
19
|
| 2018 PT23 |
2018-Aug-16
|
5.6 LD
|
15.8
|
46
|
| 2018 PL10 |
2018-Aug-18
|
19.4 LD
|
12.5
|
134
|
| 2018 PO22 |
2018-Aug-18
|
8.9 LD
|
11.1
|
86
|
| 2018 PK20 |
2018-Aug-18
|
7.9 LD
|
8.3
|
24
|
| 2018 QE |
2018-Aug-20
|
2.8 LD
|
4.5
|
10
|
| 2018 PK9 |
2018-Aug-22
|
17 LD
|
9
|
33
|
| 2018 PW7 |
2018-Aug-23
|
11.3 LD
|
10.6
|
47
|
| 2018 PU23 |
2018-Aug-23
|
7.8 LD
|
1.5
|
8
|
| 2018 PR9 |
2018-Aug-24
|
18.1 LD
|
14
|
46
|
| 2018 LQ2 |
2018-Aug-27
|
9.4 LD
|
1.5
|
39
|
| 2016 GK135 |
2018-Aug-28
|
16.8 LD
|
2.8
|
9
|
| 2016 NF23 |
2018-Aug-29
|
13.2 LD
|
9
|
93
|
| 1998 SD9 |
2018-Aug-29
|
4.2 LD
|
10.7
|
51
|
| 2018 DE1 |
2018-Aug-30
|
15.2 LD
|
6.5
|
28
|
| 2001 RQ17 |
2018-Sep-02
|
19.3 LD
|
8.3
|
107
|
| 2015 FP118 |
2018-Sep-03
|
12.3 LD
|
9.8
|
490
|
| 2018 QA |
2018-Sep-03
|
17.5 LD
|
20.4
|
73
|
| 2017 SL16 |
2018-Sep-20
|
8.5 LD
|
6.4
|
25
|
| 2018 EB |
2018-Oct-07
|
15.5 LD
|
15.1
|
155
|
| 2014 US7 |
2018-Oct-17
|
3.2 LD
|
8.7
|
19
|
| 2013 UG1 |
2018-Oct-18
|
10.4 LD
|
13.4
|
123
|
| 2016 GC221 |
2018-Oct-18
|
8.7 LD
|
14.4
|
39
|
Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Table from SpaceWeather.com
Near-Earth objects (NEOs) discovered this month: 103, this year: 1075, all time: 18627.
Potentially hazardous asteroids: 1912 (as of August 21, 2018)
Minor Planets discovered: 779,736 (as of July 31, 2018)
Fireballs
On Aug. 20, 2018, the NASA All Sky Fireball Network reported 10 fireballs.
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. Source: Spaceweather.comThe Solar System
This is the position of the planets and a couple spacecraft in the solar system:
Position of the planets in the inner system, Aug 21 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
Position of the planets in the middle system, Aug 21 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.Exoplanets
Confirmed Exoplanets: 3,777 (8/16/2018)
Multi-Planet Systems: 625 (8/16/2018)
Kepler Candidate Exoplanets: 4,496 (8/31/2017)
TESS Candidate Exoplanets: 0
Data from the NASA Exoplanet Archive
Apps used for this post:
Stellarium: a free open source planetarium app for PC/MAC/Linux. It’s a great tool for planning observing sessions.
NASA Eyes on the Solar System: an immersive 3D solar system and space mission simulator – free for the PC /MAC.
I maintain the unofficial NASA Eyes Facebook page.
2018 is NASA’s 60th anniversary!P.S. My cat Deimos was trying his hardest to make it difficult for me to write this post…
