Question

1. choose all that apply.

choose two facts about short - period and long - period comets.
short - period comets are faster and less dense than long - period comets.
long - period comets have very strange orbits and might be from the oort cloud.
short - period comets can originate near jupiter with a period of about 20 years.
long - period comets are larger than short - period comets.

1. choose the best answer.

____ design and maintain spacecraft such as rockets and space probes and ensure that spacecraft work and are safe
exoplanetary scientists
astronomers
astronautical engineers
astronauts

Explanation:

Question 11:

To solve this, we analyze each option:

• "Short - period comets are faster and less dense than long - period comets": Short - period comets have shorter orbital periods (faster in terms of orbital motion) and are generally less dense than long - period comets. This is a valid fact.
• "Long - period comets have very strange orbits and might be from the Oort cloud": Long - period comets have highly eccentric and strange orbits and are believed to originate from the Oort cloud. This is correct.
• "Short - period comets can originate near Jupiter with a period of about 20 years": Short - period comets (also called Jupiter - family comets) do originate in the vicinity of Jupiter's orbit and have periods typically less than 20 years (some around 20 years). This is correct.
• "Long - period comets are larger than short - period comets": There is no general rule that long - period comets are larger than short - period comets. So this is incorrect.

We need to choose two facts. The two correct facts are "Short - period comets are faster and less dense than long - period comets" and "Long - period comets have very strange orbits and might be from the Oort cloud" (or "Short - period comets can originate near Jupiter with a period of about 20 years" and one of the other correct ones, but the most well - known two are the first two in terms of general comet knowledge).

• Exoplanetary scientists: Study exoplanets (planets outside our solar system), not spacecraft design.
• Astronomers: Study celestial objects, their properties, etc., not spacecraft design and maintenance.
• Astronauts: Are the ones who travel in space, not design and maintain spacecraft.
• Astronautical engineers: Are responsible for the design, development, and maintenance of spacecraft like rockets and space probes to ensure they work safely.

Answer:

The two correct options are:

• Short - period comets are faster and less dense than long - period comets
• Long - period comets have very strange orbits and might be from the Oort cloud

Question 12: