There are plenty of astronomical events every year. The Hong Kong Space Museum staged a special exhibition at the Foyer to introduce six spectacular events in 2020. The exhibition presented the details of the events and explain the phenomena. It serves as a practical guide to show you how to pick the best dates, times, locations and tools for observations. The six spectacular events are: "grouping of four planets with the Moon" in late March, "serial phenomena of Jupiter's moons" on 11 - 12 June, "partial solar eclipse" on 21 June, "Perseid meteor shower" in mid-August, "Geminid meteor shower" in mid-December and "Jupiter-Saturn conjunction" on 21 December. The first three events were introduced in the exhibition from January to June while the remaining three were introduced from June to September.
Mercury, Mars, Jupiter, Saturn and Moon have different orbital periods and rarely gather together from the viewpoint on Earth. They group closely in the east to southeast direction on these nights coincidentally.
Ease of Observation |
Easy to Medium |
How to See? |
With the naked eye or a telescope |
Where to See? |
A location with an unobstructed view of the sky and horizon in the east to southeast direction |
When to See?
04:00 to 05:30
The first three planets (Mars, Jupiter and Saturn) group with the Moon one-by-one, which is easy to observe.
05:30 to Sunrise
The last planet Mercury rises above the horizon and completes the grouping. However, due to the low altitude of Mercury, it is difficult to observe.
What to See?
Why?
To Know More
The individual dates of planet-Moon conjunctions:
| Date | Hong Kong Time | |
| Mars-Moon conjunction | 18/3/2020 | 16:18 |
| Jupiter-Moon conjunction | 18/3/2020 | 18:18 |
| Saturn-Moon conjunction | 19/3/2020 | 07:56 |
| Mercury-Moon conjunction | 22/3/2020 | 01:48 |
Hong Kong Space Museum's stargazing mobile App (Star Hoppers) can simulate the "Grouping of Four Planets with Moon". Simulation of 18/3/2020 05:30 is used as an example below:
Instructions:
1. Run the "Star Hoppers" App
2. Tap the date and use the control bar on the right to adjust the date to "2020/03/18".
3. Tap the time and adjust the time to "05:30".
4. Point the camera to the southeast sky, the screen will show "Grouping of Four Planets with Moon".
Download Star hoppers:
iOS version
Android version
The upcoming similar event:
15-17/4/2020: "Grouping of Three Planets (Jupiter, Saturn and Mars) with Moon"
A series of "eclipse", "transit" and "occultation" phenomena of three Jupiter's Galilean moons happens within a few hours on this night.
Ease of Observation |
Difficult |
How to See? |
Observe with an astronomical telescope of 10 cm aperture or more, with at least 100× magnification |
Where to See? |
A location with an unobstructed view to the horizon in the southeast direction (before 23:00, 11/6), and also in the southeast to southwest direction (after 23:00, 11/6) |
When to See?
What to See?
This video simulates the telescopic view of the event between 21:30 11 June and 05:00 12 June 2020 (Hong Kong Time). (In this computer simulation, the positions of Jovian surface features such as the Giant Red Spot can differ from reality.)
Why?
Jupiter's moons are in constant orbit around Jupiter. Changes in the relative positions of the Sun, the Earth, Jupiter and Jupiter's moons lead to one of the below three kinds of phenomena. Multiple phenomena can occur simultaneously..
To Know More
Click here to watch the Jupiter's moons phenomena in 2015 recorded by the Griffith Observatory.
Jupiter looks blurry because undulations in the atmosphere distort the fine details seen through the telescope. The atmospheric distortion reduced between 03:20 and 03:30 of the video.
Galilean moons
| Name | Radius (km) | Orbital period (day) | Greatest magnitude | |
| Jupiter I | Io | 1,821.6 | 1.769 | 5.0 |
| Jupiter II | Europa | 1,560.8 | 3.551 | 5.3 |
| Jupiter III | Ganymede | 2,631.2 | 7.155 | 4.6 |
| Jupiter IV | Callisto | 2,410.3 | 16.69 | 5.7 |
The upcoming similar events:
25/3/2020
18/5/2020
25/5/2020
19/6/2020
11/8/2020
About 85% of the solar disc area is being blocked by the Moon at the greatest eclipse seen in Hong Kong.
Ease of Observation
Easy
How to See?
Safety Tips
1. Never look at the Sun directly with the naked eye. Although part of sunlight is blocked, the remaining intense sunlight may still cause permanent damage to your eyes.
2. Even if you use a suitable equipment, make sure that it is used properly during observation and you should inspect it from time to time.
Safe Solar Observing
Unsafe Solar Observing
Where to See?
When to See? What to See?
The Sun is not drawn to scale
Why?
When the Moon passes between the Sun and the Earth, the observers under the shadow of the Moon will see the disk of the Sun being obscured by the Moon.
To Know More
Download the "Pinhole Projector" sample (print on a A4 size paper) (Click here to download)
Video introducing the partial solar eclipse on 21 June 2020 (made by Hong Kong Observatory, content is available in Chinese only)
Time lapse video of partial solar eclipse captured by the solar telescope
The upcoming solar eclipse visible in Hong Kong:
20/4/2023 (partial solar eclipse)
Watching from a dark rural location with a wide field-of-view, you may be able to see 20 to 30 meteors per hour under favourable weather conditions.
Ease of Observation
Medium
Why?
"Meteoroids" are natural debris and rocks sized between 0.03 mm and 1 m. A "meteor" is the streak of light crossing the sky resulting from the high-speed entry of a meteoroid into the atmosphere. A "meteor shower" is formed when the Earth passes a swarm of meteoroids with similar orbits sharing a common origin.
What to See?
When to See?
In Hong Kong, the best time to observe is about 05:00, 13 August for the Perseid meteor shower and 02:00 to 03:00, 14 December for the Geminid meteor shower. Try the nights before and after if weather permits.
Meteor Showers Q&A
Q: An outburst? I wish I can see meteors coming down like a shower!
A: Probably not, don't expect too much. Although the Zenith Hourly Rate (ZHR) of both meteor showers is over 100, there are unfavourable factors such as light pollution and presence of clouds, etc. Even under ideal conditions, there may only be 20 to 30 meteors visible per hour. Other factors include:
- Peaking time of the meteor shower activity
- The location of the radiant point in the sky
- Moon phase
Q: How does a meteor shower link with a constellation?
A: A meteor shower is named by the constellation where its radiant is located. For example, the radiant of the Geminid meteor shower is in the constellation Gemini.
Q: Where to See?
A: Go to a dark place with little light pollution, such as a rural area. Light pollution causes a significant drop in the number of observable meteors. You may not even see a single one in urban areas!
Find a site with a wide field-of-view. The wider the view of the sky, the higher the chance to see more meteors.
Q: Should I gaze at the radiant?
A: Not necessarily. Meteors may appear anywhere in the sky. It is better to look everywhere.
Q: Why red light torches?
A: Red light is preferred for maintaining night vision. A red light torch can be easily made by covering a regular torch with layers of red cellophane, cloth or plastic bag.
Q: Shall I lie down and use the naked eye?
A: This is smart. You'd better lie down enjoying a wide view of the sky and count the number of meteors with the naked eye.
Q: Shall I use a telescope?
A: This is unwise. The narrow field of view through a telescope decreases your chance of seeing meteors.
To Know More
Click here for the details of Geminid Meteor Shower 2020
Click here for the calendar of major meteor showers
Click here to know more about ZHR (Zenith Hourly Rate) calculation: Meteor stream activity
Video introducing meteors and comets (made by Hong Kong Observatory, content is available in Chinese only)
In the evening of 21 December, Jupiter and Saturn are visually in close proximity to each other. They are apparently separated by only about six arc minutes, or one-fifth of the size of the Moon. The event is known as "Jupiter-Saturn conjunction", which is a rare phenomenon repeating roughly every two decades. The two planets are still very close a day before and after the date of conjunction and is a treat for the eyes.
Ease of Observation |
Easy to Medium |
How to See? |
With the naked eye or a telescope with 130 to 300× magnification |
Where to See? |
A location with an unobstructed view of the sky and horizon in the west-southwest direction |
When to See? |
18:00 to 19:30 |
Why?
From the viewpoint on Earth, Jupiter and Saturn are apparently very close to each other, but they are actually separated by about 730 million km.
What to See?
This video simulates the telescopic and the naked eye views between 18:00 to 19:30 each day on 20, 21 and 22 December 2020 (Hong Kong Time).
To Know More
The upcoming similar event:
5/11/2040
