How to See Asteroids With A Telescope?

We see night sky objects through a telescope because they reflect sunlight. Asteroids do the same thing which means it is possible to view them from the earth through a suitable telescope. In fact, sometimes it becomes indistinguishable from the stars though the distances between the asteroid and stars from the earth are different. Asteroids are a few million kilometers from the earth which means they move fast in the night sky compared to the background stars. This is how you can distinguish asteroids from the other objects in the sky. However, Main Belt asteroids are bigger than near-Earth asteroids (NEA). So we can not see near-earth asteroids through the telescope because of their sizes.

What are Asteroids?

Space object asteroids are celestial bodies that vary in size, ranging from small rocks a few meters in diameter to large objects over 1000 kilometers in size. They exhibit a diverse array of surface features, including rocky remnants from the formation of the solar system, impact craters, regolith, boulders, and in some cases, evidence of past volcanic activity. The composition of space object asteroids consists of rock, metal, and sometimes water, leftover from the formation of the solar system. They are generally smaller than planets and larger than meteoroids, with an average density of around 1.5 g/cm^3.
The most common spectral types of space object asteroids are C-type, M-type, and S-type, with C-type asteroids being the most prevalent, making up approximately 75% of known asteroids. S-type asteroids, which constitute about 17% of all asteroids, have a siliceous composition and relatively high density. The average albedo of asteroids is approximately 0.15, meaning they reflect about 15% of the sunlight that hits them, influencing their visibility through telescopes.

Can you see Asteroids with a telescope?

Yes, you can see space object asteroids with a telescope, but the optical quality of the view is affected by factors such as composition, size, shape, distance, and the resolving power of the telescope. The minimum magnification needed to view asteroids with a telescope is between 150x and 200x, with a minimum of at least 100x suggested. The aperture of a telescope plays a crucial role in determining the visibility of asteroids through a telescope by impacting the light-gathering ability and resolution of the telescope. The ideal focal ratio for observing asteroids with a telescope is around 10, but it ultimately depends on the balance between field of view and magnification, as well as individual preferences and observing conditions.

Quick Guide to Observe Asteroids 

A website called the IAU Minor Planet Center has resources to direct you in finding asteroids. On that night, search for an object with a magnitude of 10 if the asteroid is brighter. You must keep in mind that because asteroids travel so quickly, you must search for them in two distinct locations at two different time.  The best time to see asteroids is when they are in opposition. It will be challenging to find asteroids on the first night if you use a 6-inch or smaller telescope. The process of identifying an asteroid will take two hours, even with an 8-inch telescope. Beginner telescopes can spot asteroids at magnifications of 150 to 200.

Before starting, choose a star chart.

If you want to find an asteroid in the night sky, you have to know the location of the asteroid at your observation time. You can use a star chart for this. The IAU Minor Planet Center is a website that contains guiding material to help you locate asteroids. There are many other software and apps available online for this task. Some of them are given below.

• Deep Space (D. S. Chandler)
• TheSky (Software Bisque)
• Guide (Project Pluto)
• Home Planet (J. Walker)
• MegaStar V4.x (E.L.B. Software)
• Earth-Centered Universe (Nova Astronomics)
• SkyMap (SkyMap Software)

Pro tip: You can enlist the asteroids available in the sky on that night with their Right Ascension and Declination. It will help you to find celestial bodies quickly and plan for your observation.

How to find Asteroids in the sky?

1. Check the astronomy app and mark which asteroids will be visible in the sky.
2. If your telescope is aligned, try to point to the correct field. Then look for the asteroid according to the chart. If the asteroid is brighter on that night, look for an object with 10 magnitudes. You have to remember that asteroids move so fast in a few minutes that you have to look for them in two different places at two different times.

What is the best time to observe Asteroids?

Main belt asteroids orbit the sun like other planets. They also reach their oppositions (opposite side of the sun from the earth) like the planets. At this time, asteroids are viewable throughout the night and reflect more light, and get brighter.

Besides, as the asteroids follow an elliptical orbit, asteroids reach their farthest and closest time. Luckily in some cases, asteroids coincidentally reach their opposition, and at the same time get closest to the sun. This incidence is called perihelic opposition. Asteroids get extra light from the sun which means they become more visible at this time.

2 Tips to observe Asteroids in the best way.

• If you use a 6-inch or smaller size telescope, the first night will be hard to detect asteroids. Even with an 8-inch telescope, it will take 2 hours to identify an asteroid.
• The more the stars are in the background, the easier it is to detect an asteroid. As it moves faster, the object that is changing its position compared to the stars is surely an asteroid.

Which Asteroids can you see with a telescope?

Here is a list of Asteroids that you can see with a telescope:

• 4 VESTA: The brightest asteroid in the asteroid belt has a luminosity of +5.6 magnitude. It can be seen with even bare eyes.
• 2 Pallas: One of the largest asteroids in the asteroid belt with an apparent magnitude of 6.49 to 10.65. It can be seen with a small telescope.
• 1 CERE: It is a dwarf planet in the asteroid belt. 1 CERE was the first asteroid discovered. It can be seen with a small-medium telescope.
• 7 Iris: A large main-belt asteroid with an Absolute magnitude of 5.51
• 433 Eros: The first discovered near-Earth S-type asteroid orbiting the sun with an absolute magnitude of 11.6.
• 3 Juno: It has a magnitude of 5.33 and is visible with a telescope.
• 6 Hebe: Current magnitude is 9.71 and is visible with a small telescope.
• 18 Melpomene: It can reach an apparent magnitude of  +7.9 and is visible with a 6-inch telescope.
• 15 Eunomia: A very large asteroid with an apparent magnitude of 7.9 to 11.24. It is visible with a small telescope.
• 8 Flora: Asteroid 8 Flora is 11.39 (JPL) in current magnitude and is visible with a 10-inch telescope.
• 324 Bamberga: Visible with a small telescope having a magnitude of 9.1 currently.
• 9 Metis: The current magnitude of Asteroid 9 Metis is 11.50 which is visible with a small telescope.
• 192 Nausikaa: A small telescope can show this asteroid with a magnitude of 11.65.
• 20 Massalia: You need a small telescope to see this having a magnitude of 11.76

Other asteroids you can see with the telescope:

• 27 Euterpe
• 12 Victoria
• 29 Amphitrite
• 11 Parthenope
• 5 Astraea
• 43 Ariadne
• 89 Julia
• 39 Laetitia
• 44 Nysa
• 19 Fortuna
• 10 Hygiea
• 14 Irene

Which telescope to see Asteroids?

Celestron NexStar Evolution 6″ Computerized Telescope, Orion 6″ f/9 Ritchey Chretien Reflect,  Sky-Watcher 180mm Maksutov Cassegrain, Meade 8″ f/4 LX85 Astrograph Reflector, and Takahashi Mewlon-210 f/11.5 Dall Kirkham Reflector are great telescopes to see Mercury. A list of telescopes to see the planet’s Asteroids has more telescope options that can see Asteroids very clearly.

What size telescope to see Asteroids?

A beginner 6-inch telescope is enough to find Asteroids. Telescopes with more than 6 inches are fair enough to reveal more details like shape and color. 

What magnification is required to see Asteroids?

Asteroids can be seen in beginner telescopes at 150x-200x magnification. If you want to see the shape of Asteroids, you have to use at least an 8-10-inch aperture telescope with 200-500x magnification power.

Enjoying Asteroids? Here are other things to see with a telescope.

Asteroids are amazing to see with a telescope. You can see the bigger nearby planets with the same telescope you use to view Asteroids. You also can see amazing comets and meteor showers. Moreover, you can see a lot of galaxies and get guidance from the article Viewing Asteroids Through A Telescope. You also can go through List of things to see with a telescope to get a list of objects you can see with a telescope.