Saturn and Venus move away from each other each evening in the southwestern sky after sunset this week – by early next week, Saturn will be very low on the horizon.
Mercury, Mars and the star Spica continue to align above the southeastern horizon before sunrise this week – Mercury is very low, and may be challenging to observe.
Mercury, Mars and the star Spica align above the southeastern horizon before dawn this week. Credit: Stellarium / Bob TrembleyThe waning gibbous Moon appears in the eastern sky around midnight on Dec. 18th, the star Regulus nearby.
Waning gibbous Moon in the eastern sky around midnight on Dec. 18th. Credit: Stellarium / Bob Trembley.A waning crescent Moon appears near the star Spica in the eastern sky around 4:00 AM on Dec. 21st.
Waning crescent Moon in the eastern sky near the star Spica at 4:00 AM on Dec. 21st. Credit: Stellarium / Bob Trembley.
Asteroid Occultations
More often than I thought, asteroids and transneptunian objects pass in front of stars, causing them to monetarily wink-out. This observing challenge is a rather more advanced than most, as it is best done with an 8 inch+ telescope, and if you intend on reporting your timings (kinda the point) you’ll need video recording equipment with time-insertion hardware, and the ability to create AVI video files.
If enough observations are made from different locations, the data can be merged, revealing an outline of the object – this is how it was discovered that transneptunian object 2014 MU69 was a bilobed object; the binary nature of asteroid 90 Antiope can easily be seen in a profile image.
Here’s a video showing the efforts to observe the 2014 MU69 occultation in 2017:
There will be an occultation of a star by a main-belt asteroid on Dec. 20th at 5:14 UTC – the shadow will pass directly over lower Michigan!
You can find a list of occultations here: http://www.poyntsource.com/New/Regions.htm
You can report occultation observations here: http://www.asteroidoccultation.com/observations/Results/
The Moon is a waning gibbous, rising after sunset, visible high in the sky after midnight, and visible to the southwest after sunrise.
The third quarter Moon occurs on Dec. 19th, rising around midnight, and visible to the south after sunrise.
After Dec. 19th, the Moon will be a waning crescent, visible low to the east before sunrise.
The Moon from Dec. 17-23, 2019. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.
The Sun has been spotless for 34 days – the longest stretch for quite some time. Large coronal holes appear at both poles, and a couple smaller holes appear near the center for the Sun’s face.
The Sun seen in 193 angstroms (extreme ultraviolet) Dec. 16, 2019:
Light prominence activity, but still good enough to point your solar telescope at.
The Sun seen in 304 angstroms (extreme ultraviolet) Dec. 16, 2019:
You can view the Sun in near real-time, in multiple frequencies here: SDO-The Sun Now.
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.
Solar wind speed is 351.1 km/sec (↓), with a density of 7.1 protons/cm3 (↑) at 1531 UT.
Facebook: SolarActivity
https://www.facebook.com/photo.php?fbid=10220653811556109&set=gm.2854098404601485&type=3&theater&ifg=1
Solar Corona
Near real-time animation of the corona and solar wind from the Solar & Heliospheric Observatory (SOHO):
Animated LASCO C2 Coronograph showing the solar corona above the Sun’s limb (the white circle). Credit: NASA/JPL-Caltech-SOHOSun News
Upcoming Earth-asteroid encounters:
| Asteroid |
Date(UT)
|
Miss Distance
|
Velocity (km/s)
|
Diameter (m)
|
| 2019 XF |
2019-Dec-18
|
9.3 LD
|
24.1
|
79
|
| 216258 |
2019-Dec-20
|
15.3 LD
|
11.8
|
324
|
| 2013 XY20 |
2019-Dec-21
|
18.3 LD
|
1.9
|
28
|
| 2017 XQ60 |
2019-Dec-22
|
11 LD
|
15.6
|
47
|
| 310442 |
2019-Dec-26
|
19 LD
|
12.3
|
372
|
| 2019 WR4 |
2019-Dec-31
|
11.7 LD
|
4.2
|
21
|
| 2019 AE3 |
2020-Jan-02
|
4.9 LD
|
8.2
|
13
|
| 2019 UO |
2020-Jan-10
|
11.8 LD
|
9.4
|
341
|
| 2019 WC5 |
2020-Jan-11
|
6.4 LD
|
13
|
107
|
| 2011 EP51 |
2020-Jan-15
|
19.6 LD
|
7.1
|
32
|
| 2017 RZ15 |
2020-Jan-15
|
12.1 LD
|
7.4
|
14
|
| 2009 BH2 |
2020-Jan-18
|
14.6 LD
|
17.9
|
118
|
| 2013 DU |
2020-Jan-20
|
15.3 LD
|
6.4
|
59
|
| 2019 TF2 |
2020-Jan-23
|
16.2 LD
|
1.6
|
18
|
| 2018 BM5 |
2020-Jan-23
|
13.1 LD
|
8.6
|
12
|
| 2018 AL12 |
2020-Jan-30
|
18.2 LD
|
17.7
|
39
|
| 2018 BU1 |
2020-Feb-02
|
19.4 LD
|
10
|
41
|
Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Red highlighted entries are asteroids that either pass very close, or very large with high relative velocities to the Earth. Table from SpaceWeather.com
Potentially hazardous asteroids: 2018 (last updated Oct. 1, 2019)
Total Minor Planets discovered: 879,694 (+23,220!!)
I created a trend-line chart using the totals for each week since last July – this shows the 1,000,000 point being crossed in 2023 – but if we keep getting these HUGE new additions each week, that will push that date way back!
On Dec. 15, 2019, the NASA All Sky Fireball Network reported 113 fireballs.
(86 Geminids, 26 sporadics, 1 Dec. Monocerotid)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). From: Spaceweather.comFireball News
https://twitter.com/UKMeteorNetwork/status/1206117260961693697
Position of the planets and a couple spacecraft in the inner solar system:
Position of the planets and some spacecraft in the inner solar system, Dec. 17, 2019. Credit: NASA Eyes on the Solar System / Bob Trembley.Position of the planets and a couple bodies in the middle solar system – the asteroid named after my wife is highlighted in red:
Position of the planets in the middle solar system, Dec. 17, 2019 – the orbit of main-belt asteroid 117852 Constance is highlighted. Credit: SpaceEngine / Bob Trembley.Position of the planets in the outer solar system, transneptunian object (TNO) and possible dwarf planet (225088) 2007 OR10 is highlighted in red:
Outer Solar System Dec. 17, 2019 – Orbit of binary transneptunian object (225088) 2007 OR10 is highlighted in red. Credit: SpaceEngine / Bob Trembley(225088) 2007 OR10, proposed to be named Gonggong, is a likely dwarf planet orbiting the Sun beyond Neptune. It is a member of the scattered disc, a high-eccentricity population of trans-Neptunian objects. 2007 OR10 is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. As of 2019, its distance from the Sun is 88 astronomical units (1.32×1010 km; 8.2×109 mi), and is the sixth-farthest known Solar System object. It was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory. The discovery was announced in January 2009.
At 1,230 km (760 mi) in diameter, 2007 OR10 is approximately the size of Pluto’s moon Charon and is the fifth-largest known trans-Neptunian object in the Solar System. It is sufficiently massive to be gravitationally rounded, thereby qualifying for dwarf planet status. Its large mass also makes retention of a tenuous atmosphere of methane just possible, though such an atmosphere would slowly escape into space. 2007 OR10 is currently the largest known body in the Solar System without an official name, but in 2019, the discoverers hosted an online poll for the general public to help choose a name for the object, and the name Gonggong won. The winning name is derived from Gonggong, a Chinese water god responsible for chaos, floods and the tilt of the Earth.
2007 OR10 is red in color, due to the presence of organic compounds called tholins on its surface. Water ice is also present on its surface, which hints at a brief period of cryovolcanic activity in the distant past. 2007 OR10 rotates slowly compared to other trans-Neptunian objects, which typically have rotation periods around 12 hours. It has one known natural satellite, provisionally designated S/2010 (225088) 1, which may be responsible for its slow rotation. – Wikipedia
Artist conception of transneptunian object (225088) 2007 OR10 / Gonggong. Credit: SpaceEngine / Bob Trembley.
Orbit of S-2010 (225088) 1 around (225088) 2007 OR10 / Gonggong. Credit: SpaceEngine / Bob Trembley.
(225088) 2007 OR10 / Gonggong seen from S-2010 (225088) 1. Credit: SpaceEngine / Bob Trembley.NASA’s Interactive Real-Time Web-based Orrery:
[iframe src=’https://eyes.nasa.gov/apps/orrery/’ height=600 percent=100 style=””]
