get the facts

Prepared a bunch of Mars facts, in case I might be called upon tonight...

Many of the temporal items are based on 11 Oct 2020 at 2300h EDT.

DISTANCE

• Earth-Mars Distance or Separation: 0.4 AU (62 million km)
• in light-time, that's 3.5 minutes
• when Mars is on the other side of Sun, light-time can be over 20 minutes
• the Sun is 8 light-minutes away from Earth
• Moon 1 to 2 light-seconds
• Mars Distance (average) from Sun: 1.4 AU (212 million km)
• it's taking the spacecraft from mid- to late-July 2020 to Feb 2021 to reach Mars, i.e. 6 to 7 months
• currently the NASA Mars 2020 Perseverance probe is travelling at 104 000 km/h
• that's 1000 times faster than you driving on the highway

When we communicate with landers and rovers, there can be significant delays.

SIZE 

Diameter, true, physical: 6800 km.

Apparent diameter: +0° 00' 22.4"
That's just 1.8" smaller than in 2018.

For comparison, the Moon is 0.5°, 30', or 1800". No, Mars is not as big as the Moon.

	Mars	Earth	Moon
mass x 10^24 kg	64.2 (1/10th)	598	7.4 (1/100th)
diameter km	6800 (½ of Earth)	12800	3500 (¼)
rotation period	24.6h i.e. 24h 40m	23.9h	27.3d

Some fun facts emerge here.

The Martian day is longer. This makes for interesting shifts for humans, back on Earth, when monitor probes, landers, and rovers. And when humans work on the surface of Mars, again, it will make for interesting times.

Also note the Moon rotation period or Moon "day" is 27.3 Terran days. Some believe the Moon does not rotate. Yes, it does.

GRAVITY

• Mars gravity is stronger than Moon 
• but it's just 0.376 of the Earth standard
• person who weighs 80 kg on Earth would weigh only 32 kg on Mars

WHERE

• Azimuth: +132° i.e. south-east
• Elevation or Altitude: +41°
• 30° higher in the sky than it was two years ago
• rise time 7:00 PM
• set time 7:30 AM
• in Pisces
• moving eastward (or to the right) which is called retrograde

OUR AIR

• our air affects the view
• Airmass: 1.5
• 50% more atmosphere than looking straight up
• 150 km of air
• Mean extincted magnitude: -2.1
• we're losing a 1/2 mag to the air
• the low elevation dims Mars and reddens it and it's already red!

APPARENT

• Magnitude: -2.6
• Jupiter right now -2.1
• Apparent RA: 01h 24m 48.1s
• Apparent Dec: +05° 33' 11"
• again, 22" in size

CONDITIONS

It's a bit hostile.

	Mars	Earth	Moon
avg temp °C	-55	13	-30
nitrogen %	3	78	0
oxygen	0.1	21	0
CO2	95	0.03	0

dust storms are fairly common

It's windy:

• highest wind speed recorded 144 km/h
• same as a category 1 hurricane on Earth
• "Very dangerous winds will produce some damage"
• that's above the Beaufort wind scale maximum rating

higher levels of radiation at the surface

water is present in vapour, ice, and snow

sunsets are blue

DATES

• near opposition (Oct 13)
• near closest approach (Oct 6)
• next opposition 2+ years from now, 26-27 months... early Dec 2022
• next closest opposition 2035

FYI

• 1 year from now
• 11 Oct 2021
• Mars will be on the other side of the Sun
• about as far away as it can get...

one Martian year is 687 days

MOTION

• Orbital Velocity: 26 km/s
• apparent hourly motion: 52"

OTHER

moons, two, small

• Phobos
• Deimos

Illuminated: 99.9%

Albedo: 0.150